652 REPTILES—IGUANIDZ. 
protrusible; maxillary teeth sometimes in a common alveolus, and sometimes soldered 
to the jaw ; gular region often provided with a pouch; back sometimes crested; feet 
four, with distinct toes; premaxillary bone single ; mesosternum anchor-shaped. 
The Jguanide are allextralimital excopt Sceloporus, but the following synopsis of those 
inhabiting North America may be of service in referring the animals to their appropriate 
genera : 
Dorsal scales carinated ; infraorbital plate long. a. 
Dorsal scales smooth or tuberculated ; nape without spine. ec, 
Dorsal region and nape more or less spinose ; body raniform. b. 
a. Cephalic plates smooth; occipital as broad aslong. . . . . SCELOPORUS. 
a. Cephalic plates rngose; secipital much longer than broad. . HALOTREPIS. 
b, External ear opening present. : : - - ‘ : PHRYNOSOMA, 
b. External ear opening none : ; . : ; DOLIOSAURUS 
ce. Infraorbital region with one long =e d. 
¢. Infraorbital region with row of short plates or scales; occipital small. 4. 
ad. Interorbital plates in two rows. ; : : ; : : . AMa. 
d. Interorbitals in one or three series. e. 
é. Occipital the largest of the cephalic plates. /f. 
e. Occipital plates no larger than the others. h. 
J. Caudal scales smooth; anterior limbs very long. g. 
jf. Caudal scales above carinate; anterior limbs moderate. . . . UTA. 
g. Ear distinct. . . : Ale te eds : : CALLISAURUS, 
g. Ear invisible. ; ; : ‘ Maree RE HOLBROOKIA. 
h. Rostral plate triangular; a row of doatee like a crest extending along 
the back from nape to tip of tail, . . . . %  #DIPSOSAURUS. 
h. Rostraloblong; no trace of a dorsal crest. . . CROTAPHYTUS. 
i. Toes enlarged under the antepenultimate phalanges forming a suboval, 
transversely lamellate space. : : : : ; , .  ANOLIS. 
i. Toes not thus enlarged. j. 
j. Tail blunt; rostral plate transversely oblong. . . . #$™EUPHRYNE. 
j- Tail pointed; rostral small, scale-like. . . . «. ##CROTAPHYTUS. 
GENUS SCELOPORUS. Wiegmann. 
Head short ; cephalic plates smooth, the occipital largest ; 2 row of moderately large 
plates begins on each side of the occipitals, passes forwards,and between the orbits becomes 
a single row, whichis bounded on each side by a very small row; superciliary region 
with one row of large plates; eyelids scaly; infraorbital plate long, sometimes with 
smaller ones at the end; internasal region with small irregular plates; inframaxillary 
plates small; external auditory meatus very distinct; nape withont spines ; gular pouch 
not marked ; dorsal scales carinated, ventral smooth, imbricated ; tail long and pointed; 
caudal and dorsal crests wanting ; toes on each foot five, unguiculate; femoral region 
with a series of distinct pores. 
ScELOPoRUS UNDULATUS Harlan. 
The Brown Swift. 
Lacerta undulata, DAUDIN. 
Uromastix wndulata, MERREM. 
