A study was made of the postulated fission-inhibiting substance located in the cephalic region of Dugesia dorotocephala. Rearing decapitated planaria in four different concentrations (25, 50, 75 or 100 ug/ml) of head or whole body extract resulted in a positive correlation between the inhibition of fission rate and the concentration of extract. The difference in inhibitory activity between the two types of extracts was three percent at maximum. The inhibitory substance was partially inactivated at 60° C. There was a direct correlation between the length of time that the extract was heated and the inactivation of inhibitor. The active substance was precipitable with ammonium sulfate. Fractionation of whole body extracts with a Sephadex G-200 column showed the presence of three peaks. The material from all three peaks exhibited inhibitory activity, possibly indicating the presence of more than one inhibitory substance. Fractionation procedures with DEAE anion exchange columns inactivated the inhibitory substance(s). The mechanism of action of the inhibitory substance(s) is not known. The animals must be exposed to the extract within 24 hours after decapitation in order for maximum inhibition to be obtained.

A comparative study of the breeding ecology of 12 raptor species was conducted in the eastern Great Basin from 1967-1970. The project was designed to determine the composition and densities, habitat selection, territoriality and predatory habits of raptorial birds in a semi-arid environment. All topics were analyzed comparatively, relating the requirements and activities of the 12 raptor species. Average yearly population densities of all species approximated 0.5 pairs per square mile. Predominant raptors were the Ferruginous Hawk and Great Horned Owl. The productivity of these and the other large raptors correlated closely with the abundance of their main food source, the Black-tailed Jackrabbit. The 12 species were able to coexist because of slight differences in their comparative ecologies. Those species most likely to be potential competitors differed significantly in their choice of nesting sites, activity periods, predation or nesting timetables. This area supports lower raptor populations than the eastern United States.

En masse foraging migrations of Ligia occidentalis Dana were conspicuous events on rocky beaches near Puerto Peñasco, Sonora, Mexico. Experiments were conducted to determine which factors of the environment contained the regulating rhythm for the migration, if indeed the event were cyclic. Experiments were conducted in the laboratory using a tide-simulation aquarium and in the field using mark and release techniques. A time-lapse photography system was used in the field to quantify isopod activity for comparison with environmental factors. A regular cycle for the foraging migration was found. It was in tune with both insolation and tidal cycles so that the isopods began their migrations at the low tides which commenced uncovering the lower intertidal zones during daylight. This resulted in a sudden shift of isopod activity from the evening low tide to the morning low tide when the tides reached spring phase.

The purpose of this paper is to critically study and analyze all species belonging to the genus Pantosteus and to determine tbe validity of the characteristics that were used to separate the genus Notolepidomyzon from the genus Pantoateus. Special reference was made to the morphology of the fontanelle and the weberian ossicles. In order to more thoroughly comprehend the reasons for Cope describing Pantosteus as a new genus and Fowler describing Notolepidomyzon as a new sub-genus and then Snyder elevating it to the status of a genus as complete a historical sketch as possible was made using all literature known and available. A description has been made of the genus, the sub-genera, and all species concerned in this study. The two critical factors which separate the genus Notolepidomyzon from the genus Pantosteus received special attention. Illustrations showing the structure of the cranium have been made of representative specimens of all species except P. generosus. The fontanelle remained constant in some species, but in others it varied greatly. The weberian ossicles vere studied and illustrations made or species within both genera. No definite critical factor could be found with the ossicles that could be used to separate the genera. It is the proposal of the writer that since the characteristics that were used to distinguish these two genera are not consistent nor completely reliable, the genus Notolepidomyzon not be recognized as separate genus, but retained as a sub-genus distinguished from the sub-genus Pantosteus primarily on the thickness of the cranium and the open or obliterated fontanelle. The material and evidence needed to support this proposal is contained in this paper.

Small mammal surveys were conducted in two geographically separated aspen areas, in the Chicken Creek Watershed Management Unit, Utah, and Break Neck Flat, Wyoming. Four small mammal species, Peromyscus maniculatus, Clethrionomys gapperi, Zapus princeps and Eutamias minimus were caught most often in both areas of the aspen ecosystem. Peromyscus maniculatus was usually the most abundant animal trapped at all locations indicating the success of this species in aspen communities. The proportion of each species trapped, however, fluctuated, likely in accordance with responses to periodic biotic and abiotic factors. This data will serve as baseline information for the U.S. Forest Service who are going to manipulate the aspen communities by burning in Wyoming and clear-cutting in Utah.

The objective of this research is to assess the effects of various quantities of supplemental food (seed) on population estimates and mortality rates of desert rodents . The supplemental food is meant to stimulate natural vegetational productivity. If food availability significantly affects the population parameters methods of population estimators previously used may be in error. Hopefully this study will aid small mannnal research by designating whether, in part, population estimates and mortality rates are in error because of high vegetational productivity. The hypothesis of this study is that supplemental food in the natural environment decreases population estimates and mortality rates of desert rodents.

The purpose of this study was to determine the species of fleas infesting the mammals of the families Cricetidae and Muridae in Utah County. This was accomplished by establishing twelve collecting stations throughout the county from which 198 mammals were collected. From these hosts, 392 fleas were collected representing three families, nineteen genera , and twenty-four species. Four species are new to the State of Utah and twenty-two species are recorded from Utah County for the first time.

This study was conducted to obtain information that could be used in the management of the Utah and Mud lake white bass fishery. It also provides data for evaluating the effect of the loss of Mud Lake on the white bass utilizing it. Determination of age, growth rate, and coefficient of condition of the Mud lake white bass were objectives in this study. The occurrence of organisms in the digestive tracts of 64 white bass as well as the movement of white bass into and out of Mud Lake were also studied. Hoop nets, a continuous mesh gill net, and an experimental gill net were used in the collection of fish. A tagging gun and plastic tags were employed in marking the captured fish. Results indicated that the Mud Lake white bass had one of the lowest growth rates and condition factors reported for white bass. This was probably due to the lack of a forage fish in their diet. Results also indicated that the Mud lake white bass was part of the Utah Lake white bass population.

Utah Lake, located in Utah County, north-central Utah, is one of the most important natural fishing lakes in the state. The spawning ecology of the white bass (Roccus chrysops) was studied in Utah Lake between 1964 and 1966. Gill nets and seining were the primary means of sampling. The spawning location was sampled every other day throughout the spring and early summer of 1966. Three major winter schooling areas were found: Provo Bay - Creer Access south to the mouth of Spanish Fork River, Lincoln Beach, and off Ludlow Barn. There appears to be extensive winter feeding and movement among the white bass populations. Immature white bass of both sexes were found in large numbers throughout the entire lake during the summer. In the early spring months, bisexual schools of mature bass concentrated in the southern portions of the lake before forming into unisexual schools in mid-April. Spawning activities were restricted to an area adjacent to Lincoln Beach, 0.25 mile and to a depth of 60 inches. Rubble, interspersed with ledge rock and boulders, were the only bottom types selected for spawning. An area surrounding Bird Island also simulated the bottom types off Lincoln Beach, but was not utilized for spawning. Gravid females were taken in the vicinity of Lincoln Beach on May 6, 1966 when water temperatures had reached 63° F. Spawning activity lasted from 10 to 15 days in mid-June in water temperatures of 69° F. Unisexual schools of gravid females were found off Creer Access a distance of three miles from the spawning grounds. Small numbers of female bass would migrate to the spawning site, spawn, and return to the vicinity of Creer Access, never remaining over the spawning site longer than to spawn. Tributaries were not utilized for spawning, although bass were sampled feeding in the Provo River in mid-August. Turbidity of Utah Lake during the spring and summer prevented any observations of spawning activity or behavior. Summer sampling throughout Utah Lake in 1965 resulted in a 2:1 (174 males - 93 females) sex ratio. However, these figures are in conclusive as they did not include gravid females.

The purpose of this study is to present an analysis and key to the larvae of the nine species of Ixodes known to occur in Utah. These are I. kingi, I. muris, I. texanus, I. pacificus, I. spinipalpis, I. marmotae, I. ochotonoe, I angustus, and I. sculptus. Larvae from the first five of these nine species used in this study were reared in the laboratory by worked cited in the secion on Analysis of Species. those of the remaining four were identified on the basis of their presence with identifiable numphal and adult forms. Host specificity, although certainly variable with some forms, also proved helpful in larval identification.