206 IGUANID.E. 
Megadactylus, Fitzing. Syst. Rept. p. 59. 
Homalosaurus, Hallow, Proc, Ac. Philad. 1852, p. 179. 
Tympanum distinct. Body depressed; no dorsal crest; dorsal 
scales small, uniform. Upper head-scales small, occipital very 
large. Two transverse gular folds, the posterior with denticulated 
border; no gular pouch. Digits with sharply keeled lamelle 
inferiorly. A long series of femoral pores. Tail rather short, de- 
pressed. Lateral teeth indistinctly tricuspid; no pterygoid teeth. 
A large sternal fontanelle. No abdominal ribs. 
South-western North America. 
1. Callisaurus draconoides. 
Callisaurus draconoides, Gray, Cat. p. 227. 
Callisaurus draconoides, Blainv. 1. c. p. 286, pl. xxiv. fig. 2; Dum. & 
Bibr. p. 326; Bocourt, . c. p. 158, pl. xvii. bis. fig. 10. 
Megadactylus draconoides, Fitzng. f. c, p. 60. 
Homalosaurus ventralis, Hallow. lc. p. 179, and in Sitgreave’s Exped. 
Zunt & Color. Riv. p. 117, pl. vi. 
Callisaurus ventralis, Baird, U.S. Mex. Bound, Surv., Rept. p. 8. 
Head small, much depressed, upper lip projecting; nostril large, 
superior; ear-opening large, vertically oval. Head-scales small, 
irregular and smooth, largest on the snout; occipital large, a little 
broader than long ; a large infraorbital scale ; upper labials rather 
large and oblique. Dorsal scales uniform small juxtaposed granules; 
ventral scales larger, flat, squarish or subhexagonal, smooth. A 
slight fold along each side. Limbs very long; the adpressed hind 
limb reaches the tip of the snout, or beyond; digits long. Sixteen 
or seventeen femoral pores on.each side. Male with enlarged post- 
anal scules. Tail long and slender, depressed, covered with small 
smooth scales. Greyish above, dotted with white; tail and limbs 
with angular dark cross bands; a white and blackish streak along 
the hind side of the thighs; lower surfaces white ; a bluish band 
(males) on each side of the belly, crossed by two [or three] oblique 
black spots ; lower surface of tail with transverse black spots. 
millim. millim. 
Total length (tail reproduced) 155 Body” seu gs 76 
Gad psi eye eins irate e'se ahas 18 Fore limb . 45 
Width of head............ 18 Hind limb... 77 
California to Texas. 
a=b. S. —?P Smithsonian Institution [P.]. 
46. UMA. 
Uma, Baird, Proc. Ac. Philad. 1858, p. 2583; Cope, eod. loc, 1866, 
p. 310 
“ Ears distinct. A very long infraorbital plate. Palate without 
teeth. Outer face of upper labials plane and broadly vertical; the 
labials themselves much imbricated, and very oblique. Scales of 
