The genus Laticauda is regarded by some workers as the most primitive member of the sea snake family Hydrophiidae. However others consider that Laticauda and "true" sea snakes (Hydrophiinae) are more likely to have had separate origins within the front-fanged "proteroglyphous" snakes (Elapidae); laticaudines are thought to be most closely allied to a group comprising terrestrial Asiatic and American coral snakes together with a Solomon Islands (Bougainville) endemic proteroglyph. The present study of laticaudine affinities is divided into three main parts:- 1) An introductory section reviews the theory supporting the analytical methods used, considers some of the biological and distributional aspects of the Elapidae sensu lato and examines current theories of relationships within the "family". 2) A wide range of external and internal anatomical features of a variety of elapids are described and states of these characters are arranged into most likely transformation series, attempts also being made to determine polarities (primitive and derived conditions). 3) In the analysis and discussion section three topics are considered:- a) The issue of monophyly of the family Elapidae is examined and a recent proposal that New World proteroglyphs represent an independent derivation from American colubrids is rejected on the basis of critical re-evaluation of the evidence alleged to support the theory. b) Intra- and inter-specific variation in Laticauda is described. c) A sample of fifteen elapid species for 89 binary characters is analysed using several numerical techniques (i.e. phenetic, compatibility and parsimony methods). The main conclusion is that although the data, with most forms of analysis, tends to support the theory that the closest allies of Laticauda are some hydrophiine sea snakes, there is a considerable amount of conflicting information. It is suggested that this uncertain situation is best reflected in a classification which treats Laticaudinae, Hydrophiinae and Elapinae as equivalent subfamilies of the Elapidae.

This study involved investigations into the neural processing of auditory information by the Australian field cricket Teleogryllus oceanicus in relation to the identification of its conspecific songs. T. oceanicus males produce three song types related to three different behavioural strategies. Although each of the three songs have very similar frequency spectra their temporal patterns are very different and highly complex, particularly the courtship song. Song type recognition therefore is likely to be based on neurones capable of producing an accurately coded response to the song patterns. Using extracellular and intracellular recording techniques, neurophysiological and neuroanatomical investigations were carried out in order to Identify auditory interneurones in the pro-thoracic ganglion capable of coding for the temporal patterns of the songs. Two examples of the ascending class of neurones were identified and shown to respond to the conspecific song patterns: ANC, which coded the temporal pattern of the calling song and ANA, which produced a correlated response to the temporal pattern of the courtship song. Further investigations showed that as a result of the frequency content, syllable rate and intensity of the song, it was the Integration of excitatory and particularly inhibitory Inputs that allowed ANA to code for the courtship song. To identify other neurones involved in this pathway the origin of the inhibitory input was investigated. The local bilateral omega neurone, ONI, was thought to mediate the inhibition. Current manipulation experiments which involved simultaneous extracellular and intracellular recordings from ANA and ONI respectively were carried out. However, these experiments showed no evidence for the existence of effective synapses between these two cells. A second type of omega neurone was identified, ON2. Although this neurone was shown to be non-spiking its response was correlated with the temporal patterns of the songs. Preliminary investigations were carried out on examples of descending and through neurones.

The population biology of the coarse fish species in two gravel-pit fisheries (A and B) in Suffolk were studied from 1974 to 1977. Simultaneously the fish caught by anglers and their angling technique were monitored by census. Environmental factors were recorded on each census occasion and the crustacean zooplankton in lake A assessed in 1975 and 1976. ... Recommendations for the management of standing-water coarse fisheries are discussed and the application of census methods evaluated.

Gamma-aminobutyric acid (GABA) has been shown to be an important inhibitory neurotransmitter in mammalian central nervous system (CNS). GABA receptors have been previously characterized in mammalian brain using 3H-GABA itself, a potent GABA agonist, 3H-muscimol, and the GABA antagonist, 3H-bicuculline methiodide. Recently, it has been suggested that 1,2,3,6 Tetrahydropyridine-4-carboxylic acid (Isoguvacine) is a potent GABA receptor agonist. It has also been reported to act as a mixed agonist/antagonist at the GABA-benzodiazepine receptor complex. The binding of 3H-Isoguvacine to frozen-thawed, rat brain synaptosomal membranes has been investigated and found to be saturable, specific and stereospecific. The pharmacology of this 3H-Isoguvacine binding site was seen to be consistent with an interaction at the postsynaptic GABA receptor site. The effects of detergent treatment on this binding site-were investigated and indicated a single site, both in control and in Triton X-lOO treated membranes. A series of benzodiazepines were shown to displace 3H-Isoguvacine bound to frozen-thawed rat synaptosomal membranes. This effect was shown to be temperature-dependent and could be blocked by picrotoxinin (10-4 M). Pentobarbitone was also seen to displace 3H-Isoguvacine binding, albeit at high IC5O values; an effect antagonized by picrotoxinin. Neither the benzodiazepines nor pentobarbitone had any effect on 3H-GABA binding in frozen-thawed membranes. In contrast, using fresh rat synaptosomal membranes, neither the benzodiazepines nor pentobarbitone had any effect on 3H-Isoguvacine binding, whereas both were shown to potentiate 3H-GABA binding. A series of conformationally-restricted analogues of GABA have been synthesized and tested using two in vitro assay systems, viz. the rat superior cervical ganglion and a radioligand binding assay. These studies revealed that the class of GABA agonist, in which the amino groups are incorporated into six-membered rings exhibit an unexpected variety of activities with respect to their ability to inhibit 3H-GABA binding; their affinity for GABA uptake sites and their interaction with the coupled GABA/benzodiazepine sites.

Quantitative samples from a gravel-pit lake in 1977 (April-December) showed higher geometric mean densities and biomasses of microcrustacea in the marginal weedbeds (907/1 and 3107ug/l) than in the open water (225/1 and 245ug/l). The weedbeds were dominated by Cyclops vernalis americanus and Ceriodaphnia pulchella and the open water by Bosmina longirostris and C. vernalis americanus. C. pulchella and B. longirostris seemed mutually exclusive . Evidence from a second gravel-pit lake (lower fish stock) indicated that this was partly caused by fish predation pressure in the first lake (higher fish stock). No microcrustacea longer than 1mm occurred in the open water. The size range in the weedbeds was 0 .1 -2 .0mm. Diversity and abundance were highest amongst Potamogeton natans where C. pulchella was most abundant, but few microcrustacea/plant associations were found. The O+ roach diet contained microcrustacea from the open water and the weedbeds (50% numerically and 68% by weight). B. longirostris (open) was the preferred food but if not abundant the roach switched to pulchella (weed). Feeding was determined by prey mobility and abundance rather than by prey size. In contrast the O+ perch diet was mainly microcrustacea of weedbed origin (63% numerically and 78% by weight). Feeding was possibly size-selective. Cyclops was the main food item. Competition for food between roach and perch seemed to be minimised; diet overlaps were most common for weedbed microcrustacea. Growth of O+ roach was average in 1977 and 1978 and good in 1979. That of O+ perch was consistently average. Perch exhibited large fluctuations in first year survival. Field caging experiments provided evidence that macrophytes may be beneficial to O+ perch growth but O+ roach grew as well without them. Improved growth rates of O+- perch in the presence of macrophytes were attributed to a greater availability of macro-invertebrates and a typical feeding strategies in the absence of macrophytes.

The investigation of the chromosomal variation in populations of the land snail Cepaea nemoralis (L.) marine snail Nucella lapillus (L.) is presented. The first study (Part 1) concerns the investigation of the karyotype of C. nemoralis in populations from a region of the Berkshire Downs (U.K.)in which there are marked area effects for both the visible and allozymic characters. The present investigation has shown that there are inter-populational differences in chromosome structure. The differences fall within the range found previously in several widespread populations in the British Isles, Northern Europe and America. There are no immediately obvious variations in chromosome structure associated with observable environmental variables. There are, however, marked non-random associations of karyomorphs within some of the "area effect populations". The implications of the distribution of the karyotypic variations between the populations are discussed. The second study (Part 11) concerns the identification of the chromosome pairs involved in the numerical (Robertsonian) and structural (inversion) polymorphisms of Nucella lapillus and the investigation of the two types of polymorphism in populations of low chromosome number. A new classification of the karyotype into five main groups A to E has been made. The chromosome pairs thought to contribute to the numerical polymorphism occur in groups A, B and C and the two inversion polymorphisms occur in groups A and C. The distribution of the two types of chromosomal polymorphism at Rottingdean, Sussex (U.K.) suggest that the inversion polymorphism from group C, and the numerical polymorphism, also from group C, occur independently of each other. The differences in the distribution of the two polymorphisms in the Rottingdean area and the differences in the distribution of the chromosome pairs involved in the numerical polymorphism in different populations are discussed.

The neural processes of acoustic information was investigated in examples of Ensifera. Sound reception by these insects has two main functions: localization and recognition of the sound source. This study investigated aspects of each of these processes.

This study Is concerned with the behavioural and ecological aspects of the acoustic interaction that occurs when two bush cricket species, Platycleis albopunctata and Metrioptera roeselii. sing together. The effects of the interaction are predominantly one-way and result in inhibition of singing activity by albopunctata, or a change in its song pattern. 'Ibis behaviour was initially described by Broughton in I965 who also described song changes in other species resulting from interactions with singing allospecifics. The present study continues this research into song modification in insects. The extent of natural variation is examined in detail in the song of albopunctata. The acoustic behaviour of this species when singing with conspecifics is also examined in detail. The songs and singing behaviour of some other bush cricket species are analysed and tested for susceptibility to modification. These latter studies, though less detailed than the study on the albopunctata/roeselii interaction, have contributed to the formation of hypotheses as to the causation of song modification. The results indicate that insects with songs of similar frequency content are liable to interact acoustically. Species which show slight readjustments in song output when singing with conspecifics are also liable to song modification especially when the song of the influencing Insect is more continuous in nature than the song of the Influenced insect. The results of the detailed analysis of the albopunctata/roeselii interaction reveal a complex interplay between endogenous rhythms of motivation displayed in the singing activity of albopunctata, and parallel inhibitory and excitatory factors from the song of the roeselii. Much of the fieldwork has been undertaken in France v/here, in many localities, albopunctata and roeselii are sympatric. Song modification in the wild is usually prevented by a negative phonotactic response by albopunctata to the song of roeselii» This response may be derived from preexisting behavioural patterns that result in 'territorial' spacing between males in grassland populations. In habitats where populations overlap, interspecific spacing develops with the onset of singing activity by the adults. In this way albopunctata is excluded from certain localities by high-density roeselii populations due to the acoustic competition between these two species.

The enlarge vagal and facial lobes of the carp are associated with the presence of large numbers of taste buds located respectively, within the oropharynx, especially on the palatal organ, and on the body surface, in particular the barbels.

The taxonomy of the Order Passeriformes, at the family level and above, is still in considerable flux. An historical review of the taxonomy, including traditional studies, and more recent works (particularly DNA-DNA hybridization), is given. The present study attempted to analyse little used characters, i.e. those on the plantar surface of the foot, of over five hundred species of bird. Large amounts of variation and homoplasy were found. Compatibility analysis (by a LeQuesne test computer program) was used to find cliques of compatible characters for families, and other groups of Passeriformes. The polarities of character state changes were hypothesized by outgroup comparison, with non-passerines from a number of orders. Some characters were found to be linked to the scansorial habit, others of reasonable use taxonomically, and yet others, not obviously adaptive, showed so much homoplasy as to be almost worthless taxonomically. Useful characters were then used to describe and define families, and in some cases other taxonomic groups, attempts were made, with varying degrees of success, to allocate 'problem genera'. The same characters were used to construct cladograms, and then other informative characters (i.e. those which define subgroups within the cladogram, but show homoplasy) were added, to produce one or more trees of each group investigated. The results were compared to those of earlier studies, based on morphological, anatomical and biochemical characters. The degree of congruency varied considerably. It was particularly interesting to find that in some cases there was a reasonable fit with the results of DNA-DNA hybridization.