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A model proposed by Wilson & Findley (1972) to test for randomness in bat homing was applied to results of homing studies on big brown bats (Eptesticus fuscus) and, when possible, to published studies on homing by other bats. Most applications of the model suggest randomness in bat homing. Ecological notes concerning parturition, parasites, populations, emergence time, flight behavior and morphology of the E. Fuescus colony are reported.

The effect of feeding Zilpaterol hydrochloride (ZH) with a 3 or 10 d withdrawal (WD) period to calf-fed Holstein steers (N=2993) on carcass characteristics and tenderness were evaluated in a feed lot experiment. Cattle were fed 0 or 8.3 mg/kg of ZH for the final 20 d of the feeding period, each treatment level was assigned a WD period of either 3 or 10 d. Treatment groups consisted of Control 3 d WD (C3) and 10 d WD (C10), and ZH fed 3 day WD (Z3) and 10 d WD (Z10). Cattle were slaughtered at a commercial facility, carcasses chilled for at least 40 hours and carcass characteristics evaluated by trained personnel. Loins (n=60) were randomly selected from each treatment group for Warner Bratzler Shear (WBS) analysis. Rib-eye area (REA) increased 3.8 cm2 for ZH fed 3 day WD cattle (P<0.01) when compared to control, and 5.4 cm2 for ZH fed 10 day withdrawal cattle (P<0.01) when compared to control. There was no significant difference in REA between ZH fed 3 and 10 d WD periods (P>0.05). A trend was observed for ZH fed 10 d WD cattle to have an increased hot carcass weight when compared to control (P=0.0589), while there was no significant difference for cattle fed ZH with a 3 day WD (P=0.3763) comparatively. There was no difference in ZH fed cattle when compared to control on; kidney pelvic and heart fat %, adjusted preliminary yield grade, calculated yield grade, marbling score, or lean and bone maturity (P>0.05). There was an increase in WBS for ZH fed cattle when compared to control for Choice 7 d and 14 d aged steaks for both WD periods. Choice Z10 steaks aged 21 d showed an increase in WBS (P<0.05) while the Z3 had no effect. Select Z3 7 d aged steaks had higher WBS when compared to control while Z10 had no effect. Oppositely, the Select Z10 14 d aged steaks had increased WBS while the Z3 had no effect. There was no difference in Select 21 d aged steaks. There was no difference in WBS between the Z3 and Z10 for any of the aging periods. Feeding Zilpaterol hydrochloride for 20 d increased carcass leanness while having little effect on carcass fat of calf-fed Holstein steers. There was no difference observed between 3 d and 10 d WD period. Zilpaterol hydrochloride treatment decreased steak tenderness, although as aging progressed there little to no difference between steaks from ZH fed and control cattle.

Asexual reproduction in the decapitated planaria, Dugesia dorotocephala, is inhibited by an extract of homogenized heads of the same or closely-related species. Decapitated planaria allowed to regenerate have reproduced asexually over 80% of the time, while those that have been cultured in a suspension of head homogenate have had asexual reproduction inhibited to less than 10%. The substance that inhibits asexual reproduction is heat labile. It requires a concentration of 2.0 heads/ml that contains .13 mg protein/ml to effectively inhibit asexual reproduction. A similar concentration of head homogenate from the related planaria, Dugesia tigrina, also contains the inhibitory substance. Head homogenate from the white planaria, Phagocata oregonensis, does not inhibit asexual reproduction. A preliminary study of other animal tissues indicates that brain homogenate from the chicken, fish, salamander, and gerbil inhibits, while a liver homogenate from these animals does not inhibit as much.

Peromyscus truel's a fairly common inhabitant of the upper sonaranlife zone of the Western States. It is an excellent laboratory anlmal with the limitation that captivity must be accompanied by forced activlty, in order to keep the animals within the limits of normal activity. This mouse is polyestrous and breeds from early spring to late fall. Observations have shown pregnancy in late September and in early February. It is the writer's belief that ovulation in the ovary occurs only when copulation has taken lace, because corpora lutea has only been found in pregnant or lactating females. The evidence is scanty however and more work will have to be done in order to prove this belief. Home range, migration, populations and food habits and not thoroughly worked out because of the difficulty of trapping in a defined quadrat among the cliffs.

Observations and collections on the breeding biology and life history of Rana pretiosa pretiosa Baird and Girard have been made in central Utah from 1962 to 1967. The frogs' activities were followed from their spring emergence untril the tadpoles metamorphosed and hibernated in the fall. Collections and observations were made at regular intervals through the entire period of summer activity. Data were gathered at the ponds and samples of the life history stages were taken to the laboratory where they were analyzed and studied. Emergence is normally during the middle of March. The males precede the larger females by three or four days. Immature frogs emerge approximately two weeks later. In Utah this species prefers small ponds of standing water grown thick with stonewort, Chara sp., and possessing a deep muck bottom from which cattails emerge. The males congregate in small areas of the pond as breeding choruses where they outnumber the females five to one. The male's call is weak and can be heard for approximately 6 to 10 meters. The eggs are laid shortly after the arrival of the females and vary in number from 147 to 1160 per clutch, the average being approximately 750 per clutch. The average size of individual eggs are as follows: Egg 2.5 mm, inner gelatinous envelope 5.0 mm, and outer envelope 10.0 mm. Hatching requires about two weeks in nature and varies between 7 and 23 days, depending upon temperature. Several factors noted which affect the frog's growth and behavior are temperature, crowding, and dissolved minerals in the water. Metamorphosis required from 122 to 209 days following ovulation. Hibernation took place during the middle of October approximately to weeks after the first freezing temperatures.

This study of the Norway rat, Rattus norvegicus (Erxleben) and its consortes was undertaken in Utah County to determine : (1} the frequency of infection of Trichinella spiralis (Owen) Railliet, the causative organism of trichinosis in humans, (2) the populations of fleas, lice and mites on the rat, and (3) the occurence of other consortes. This study covered a period from January 1951 through June, 1951. Additional records were made available from studies being made by the Department of Zoology and Entomology, Brigham Young University on parasitic arthropods (listed as Project Ten). The species ot fleas, and those mites which could be determined to the species were studied in relation to population of the consors, habitat, and sex of the rat host. Emphasis was placed on the population aspect ot the consors of the rat.

This study is concerned with a critical analysis of species and subspecies of Uta stansburiana as it occurs in the Eastern Great Basin. In this study Urosaurus ornatus wrighti is also briefly discussed since it was until recently considered a member of the genus Uta and since it extends in the area which has been dealt with in this thesis. This problem necessitated study of large series of lizards in order to work out subspeciation. The material from the Brigham Young University collection and the specimens collected by the author total 520. After recording dorsal scale counts, prefrontal scales, keelation of dorsal scales, and various measurements, the two subspecies were ascribed to the following areas. Uta s. stansburiana ranges throughout Eastern Oregon, Idaho, most of the Eastern Great Basin and south to Northern Arizona. Uta s. stej, negeri ranges from Northern Mexico, Western Texas, and most of New Mexico north into Southern Utah and Southern Nevada. In order to support this study four drawings and two distributional maps have been made as well as five tables showing the taxonomic records of the subspecies.