144 Bulletin of Laboratories of Denison University. [Voi. xi. 
Family. Helodermatidae. 
The Gila monsters are the only lizards with venom-secret- 
ing glands but they are fortunately so sluggish as to rarely 
strike even when disturbed. They may be recognized by their 
large size, tubercular skin and snake-like dentition. 
Genus. Heloderma. 
Characters of the family. 
Heloderma Suspectum, Cope. 
Description : Large, heavily set, clumsy in form, with 
short legs and tail; nostrils large, opening laterally between 
three plates; eye small; ear opening large oblique; rostral and 
symphyseal plates large; a pair of internasals; three pairs of 
plates behind the symphyseal; gular region with the small tuber- 
cles passing into the plates of the belly ; upper parts covered 
with smooth convex tubercles, separated by granules, lateral 
tubercles passing into the squarish plates of the belly ; a pair 
of enlarged preanal plates. 
Color: Upper parts variously and irregularly marked with 
dark brown and salmon color ; tail sometimes ringed ; belly 
orange or salmon, with tessalted markings of brown. 
The Gila monster probably occurs in this territory only in 
the southwestern portion. 
Family. Teiidae. 
New world lizards related to the true lizards of Europe 
(Lacertidae). Head shields free from the cranial ossifications ; 
nasals double, frontal are parietal single ; tongue slender and 
ending in two smooth points ; head covered with large, regular 
plates ; ear opening and eyelids usually present ; femoral pores 
may be present. A very large family represented within our 
limits by a single genus. 
Genus. Cnemidophorus. 
Four pentadactyl limbs ; head plates large ; two frontopa- 
rietal plates ; back and sides covered with small uniform gran- 
ules; ventral plates large and serially arranged; eye lids and ear 
