In this study 883 specimens of the woundfin minnow (Plagopterus argentissimus Cope) from the Virgin River in Utah, were weighed and measured. Ratios of body measurements to standard length, and gonad weight to total weight were calculated. From the gonad weight:total weight ratios it was determined that woundfins spawn during a period from April through June, and that the first significant gonad development is during the third year of life. Several body proportions such as, snout length, gape, upper jaw length and peduncle depth grew nearly isometrically. Growth of other body proportions was more or less allometric. Head length, body depth and mouth length showed gradual changes. Pectoral fin length, eye length and total length showed rather marked allometry. The ratio of dorsal fin height to dorsal fin length also showed rather marked allometry.

Growth rates, gestation period, litter size, reproductive age, sex ratios, and development were studied on 198 litters of Reithrodontomys megalotis megalotis. Growth was characterized by several standard skull and body measurements, and was partitioned into four phases of 1-3, 4-12, 13-22, and 23-70 days. Growth was best described by measurements of tail length, ear length, and dried eye lens weight. Reproductive activity began as early as 38 days for females and 59 days for males. Gestation period was 22 days and mean litter size was 3.83 (range 1-7). Sex ratio was 53.49% males to 46.51% females. Reproductive efficiency was 53.53%. The development of R. m. megalotis was very similar to that of R. m. dychei. Early breeding, post-partum estrous, year-round breeding, high reproductive efficiency, and a short gestation period contribute to a high reproductive potential in R. m. megalotis.

Field populations of Margarites pupillus (Gould), a numerically abundant prosobranch mollusc occuring on rocky shores in Puget Sound, Washington, have previously received little autecological attention. Seawater table studios and SCUBA observations led to the following conclusions: Populations of Margarites are primarily subtidal. Population density and growth are directly related to algal canopy density. Algal canopy may function in reducing predator efficiency, Margarites populations have a 1:1 sex-reatio and no size dimorphism. Sexually mature individuals live for at least two years, and possibly more than four years.

The marked pattern and coloration which distinguish members of Crotaphytus collaris baileyi in its western range indicated a need to compare it to the collaris-complex consisting of C.c. auriceps, C.c. baileyi, and C.c. fuscus. Thirty-two external and sixteen cranial characters were measured on preserved specimens. Blood serum proteins were compared by disc gel electrophoresis. Cluster, canonical, and discriminant analyses were used to define population characteristics and areas of intergradation. Disc electrophoresis did not reveal consistent population differences. The western range of C.c. baileyi is restricted to Central Arizona. The Great Basin form from western Arizona, western Utah, southern Idaho, southeastern Oregon, Nevada, western California and northern Sonora, Mexico is proposed as a previously unrecognized subspecies, C.c. bicinctores. C. dickersonae, which is closely related to C.c. bicinctores, is reclassified as C.c. dickersonae. The population from Isla Angel de la Guardia is designated C. insularis insularis. The southern California, Baja California form is proposed as a previously unrecognized subspecies, C.i. vestigium.

Partitioning space and time by seemingly sympatric rodents, Zapus princeps and Peromyscus maniculatus, were examined as possible mechanisms allowing coexistence. The two populations were studied in Central Utah with an electrically monitored grid. Spatial separation of individuals and the populations minimized confrontations and created local allopatric distribtuions. Temporal partitioning was not used as a mechanism to allow coexistence and was apparently independent of spatial partitioning. The Peromyscus population was composed primarily of males which may have been due to less favorable habitat and/or presence of Zapus. The data show that Peromyscus tend to avoid Zapus, possibly due to deleterious aggressive behavior.

Cartilage from newborn mice homozygous for chondrodysplasia contains normal quantities of protein and chondroitin sulfate. Mutant fetal cartilage incorporates normal amounts of sulfate, glucose, and glucosamine. Overnight rinsing with water removes about 25% of the incorporated sulfur and existing uronic acid from mutant ribs and about 55% from mutant limbs. Control ribs and limbs are affected very little by such a rinse. The diffusability of chondroitin sulfate (represented by incorporated sulfur and uronic acid) may be due to a lack of covalent bond formation between chondroitin sulfate and collagen.

The neogastropod Amphissa columbiana is found abundantly in subtidal areas of the San Juan Archipelago. Two populations studied were composed of distinct age classes of sexually immature and mature specimens. Reproduction appears to take place in the fall by snails at least two years old. Amphissa is a chemoreceptive scavenger that usually feeds on carrion and on dead and injured animals. Feeding behavior is mediated by chemical attractants from dead and traumatized tissue. An unusual feeding association is formed where Amphissa congregate around feeding predators to share their meals. A specific defense mechanism is deployed by Amphissa especially in response to aggressive sea stars. In addition to using common shell twisting gyrations etc., seen in many gastropods, the proboscis of an Amphissa is inserted into the ambulacral groove of a sea star. The star responds by retracting its tube feet, lifting its ray and releasing the captured Amphissa. The radial nerve of the star may be involved in the pr[o]boscis attack.

Observations of reproductive behavior, growth and development of the young, food habits, habitat preference, and daily and seasonal activity patterns of the Colorado chipmunk are presented for the first time. The breeding cycle is as follows: mating occurs in late February or early March; the young are born in early to mid-April and first appear above ground in May, but do not reach breeding age until the following spring. There is only one litter of young per year. The mean number per litter was 5.7 for three litters born in captivity. The sex ratio of the animals born in captivity and animals observed in the field was 1:1. The average weight at birth was 3.05 g and the daily increase in weight was 0.52 grams for 90 days. The eyes were opened 29 to 33 days after birth. The pinnae unfolded in 2 to 3 days and the auditory meatuses opened when 28 to 29 days old. The eruption of the teeth were as follows: the lower incisors appeared in 10 to 12 days, the upper incisors in 20 to 22 days, and the cheek teeth appeared in 34 to 37 days. The dorsal dark and white stripes appeared in 10 days. Colorado chipmunks at Arches National Monument are found in association with juniper-pinyon areas along solid rock ledges with tumbled rock masses at their bases and on higher ridges and ravines where the soil is rocky, and to some extent associated with the blackbrush and Indian rice grass of sandy flats near juniper-pinyon areas. The seeds or fruits of the following plants were most often eaten: Indian rice grass (Oryzopsis hymenoides), Russian thistle (Salsola kali), squawberry (Rhus trilobata), cliff rose (Cowania mexicana), and juniper (Juniperus osteosperma). The chipmunks do not become active until after sunrise and as the temperature increases to its midday maximum the activity of the animals decrease to a midday minimum. The chipmunks are inactive above ground from late November until late February. It is suggested that during this period the chipmunks alternate between sleeping and feeding from their food stores. Juvenile Colorado chipmunks molt twice during their first year and it is suggested that the adults also molt twice each year. The molt proceeds anterior to posterior in June and July and progresses posterior to anterior in the September-October molt.

The chiton Mopalia muscosa ranges from the open rocky coast to the bay environment, whereas the related chiton Mopalia lignosa is restricted to the outer rocky coast. The mantle cavity currents, anatomy and histology were investigated. Mucous gland cells of Mopalia muscosa are goblet type secretory cells. Their apparent ability to deliver their secretion rapidly together with having a short restitution period probably accounts for Mopalia muscosa having success at invading the bay environment. The mucous glands of Mopalia lignosa consist primarily of cells with medium to coarse secretory granules. These cells apparently are not as efficient at handling suspended sediments thereby limiting in part the range of Mopalia lignosa. The distribution of cilia in the mantle cavity is correlated with secretory cell type. Mantle cavity and gill anatomy along with their currents are similar in the two chitons.

This paper deals with the complete skeletal anatomy ot Bolitoglossa rufescena (Cope). All parts are figured and described. In addition to this many of the main skeletal parts of Bolitoglossa platydactyla (Cuvier) Bolitoglossa occidentalis Taylor, and Bolitoglossa flaviventris (Schmidt) are described and figured. A comparison of the following parts of the above mentioned salamanders is presented: skull, atlas, ninth trunk vertebra, sixth caudal vertebra, carpals, tarsals and digits. The similarities and differences are pointed out as they appeared to the author. The relationship and specialization ot these species is discussed rather briefly.