. Bulletin. Science; Natural history; Natural history. GP RAY GA Figure 3. Comparison of suggested muscle action of M. adductor mandibularis externus in closing the jaw as suggested by Ray for Gopherus polyphemus (GP) and the present study for Gopherus agassizi (GA). The dark area on the right side of the Gopherus agassizi skull shows the relative position of the os transiliens. The symbols used in the figure include: a. tendon of M. adductor mandibularis ex- ternus; b. posterior belly of M. adductor mandibularis externus portio superficialis-. c. posterior belly of the M. adductor mandibulari
. Bulletin. Science; Natural history; Natural history. GP RAY GA Figure 3. Comparison of suggested muscle action of M. adductor mandibularis externus in closing the jaw as suggested by Ray for Gopherus polyphemus (GP) and the present study for Gopherus agassizi (GA). The dark area on the right side of the Gopherus agassizi skull shows the relative position of the os transiliens. The symbols used in the figure include: a. tendon of M. adductor mandibularis ex- ternus; b. posterior belly of M. adductor mandibularis externus portio superficialis-. c. posterior belly of the M. adductor mandibularis externus portio profunda. by bone. It also appears that the os transiliens ossifies earlier in young individuals of Gopherus agassizi than in other species studied. The os transiliens seems to be a device to smooth the translation of the horizontal pull of the M. adductor mandibularis ventrally in pulling the mandible shut. I wish to thank Bayard Brattstrom and James Smith lor their assistance in this study and for reviewing the manuscript. LITERATURE CITED Evans, H. E. 1968. Clearing and staining small vertebrates, in toto, for demonstrating ossifica- tion. Turtox News. 26(2) Gaffney, E. S. 1972. An illustrated glossary of turtle skull nomenclature. Amer. Mus. Novit., 2486:1-33. Inman, V. T. 1947. Functional aspects of the ab- ductor muscles of the hip. J. Bone Surg. (Amer.), 29:607-619. Legler, J. M. 1962. The os transiliens in two spe- cies of tortoises. Genus Gopherus. Herpetologica, 18:68-69. Ray, C. E. 1959. A sesmoid bone in the jaw musculature of Gopherus polyphemus (Reptilia: Testudinina). Anatomischer Anzeiger, 107(1/5): 85-91. Willey, R. B. 1969. Staining shark skeletons with alizarin Red S. Turtox News, 47(2):50-52. Robert Patterson, Dept. Biology, California Slate University, Fullerton, California 92634. Accepted for publication November 27, 1972. RATE OF HEAT LOSS BY LARGE AUSTRALIAN MONITOR LIZARDS Bartholomew and Tucker (1964) have shown that there is
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