OSTEOLOGY AND MYOLOGY OF THE HEAD AND NECK REGIONS OF CALLISAURUS, COPHOSAURUS, HOLBROOKIA, AND UMA (REPTILIA: IGUANIDAE) Douglas C. Cox' and Wilmer W. Tanner^ Abstract.-A detailed study of the anterior osteology and myology of Callisatmis, Copho.saurus, Holbrookia, and Vma reveals the phylogenetic relationships among the sand lizards. An SPSS discriminant analysis of os-teological characters combined with myological characters indicates that Callimiirtis is most primitive, Cop-hosaurus and Holbrookia are most closely related, and Uma is the most distinct of the sand lizard genera. Be-cause of close relationships between Cophosaurus and Holbrookia, it is postulated that earlessness evolved once, and Cophosaurus is returned to synonymy under Holbrookia. Blainville (1835) wrote the first descrip-tion of a sand lizard and named it Calli-saurus draconoides. Since then various au-thors have pubhshed articles concerning sand lizards. Girard (1851) described Hol-brookia maciilata, Trochel (1852) described Cophosaurus texanus, and that same year Baird and Girard synonymized Cophosaurus with Holbrookia, providing the name Hol-brookia texana, which then remained un-changed for over 100 years. Subsequently, Baird (1858) described Uma notata. By 1858 all genera represented in the sand lizard group had been described. Since then new species and subspecies, as well as new combinations, have been added by var-ious authors as follows: Bocourt (1874) Hol-brookia elegans-Cope (1880, 1883, 1894, 1895, 1896, 1900) Holbrookia lacerata, Hol-brookia maculata fkwilenta, Uma scoparia, Uma inornata, Uma rufopuncatata, Calli-saurus crinitus, Callisaurus rhodostictus, Holbrookia maculata maculata, Callisaurus draconoides ventralis, and Callisaurus ven-tralis gabbii; Stejneger (1890) Holbrookia maculata approximans and Holbrookia maculata lacerata; Richardson (1915) Calli-saurus ventralis myurus; Dikerson (1919) Callisaurus carmenensis; Schmidt (1921, 1922) Holbrookia maculata campi, Hol-brookia pulchra, Holbrookia dickersonae, and Callisaurus ventralis inusitatus; Schmidt and Bogert (1947) Uma exsul; Barbour (1921) Holbrookia thermophila; Harper 'Department of Zoology, Brigham Young University, Provo, Utah 84602. 'Life Science Museum, Brigham Young University, Provo, Utah 84602. (1932) Holbrookia propinqua stonei; Smith (1935, 1943, 1946:137, 145) Holbrookia ele-gans thermophila, Holbrookia elegans ele-gans, Holbrookia bunkeri, Holbrookia macu-lata ruthveni, Holbrookia maculata dickersonae, Holbrookia maculata pulchra, and Holbrookia maculata thermophila; Lins-dale (1940) Callisaurus draconoides myurus and Callisaurus draconoides gabbii; Heifetz (1941) Uma notata notata; Bogert and Dor-som (1942) Callisaurus draconoides brevipes; Smith and Burger (1950) Holbrookia prop-inqua propinqua and Holbrookia propinqua piperata; Peters (1951) Holbrookia texana texana and Holbrookia texana scitula; Axtell (1956) Holbrookia lacerata, Holbrookia lacer-ata subcaudalis and Holbrookia maculata perspicua; Smith and Cochran (1956) Calli-saurus draconoides rhodostictus; and Wil-liams, et al. (1959) Uma paraphygus. Some summaries, reviews, checklists, and comparative studies have also been written. Cope (1896) synonymized Uina and Calli-saurus in a short paper di.scussing the genus Callisaurus. He recognized Uma again in his large work on the crocodilians, lizards, and snakes of North America (1900) and recognized one species and three subspecies of Callisaurus. Smith (1946:137, 145), in his "Handbook of Lizards," recognized in Callisaurus one species and ten subspecies and stated (p. 145): 'The whole group of Callisaurus of 35
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