652 REPTILES—IGUANIDA. 
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 Iguanide are all extralimital except 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. . * 
Dorsal region and nape more or less spinose ; body raniform. Db. 
a. Cephalic plates smooth; occipital as broad aslong. . . . . SCELOPORUS. 
a. Cephalic plates rugose; occipital much !onger than broad. . HALOTREPIS. 
6b. External ear opening present. ; : : 5 ° : PHRYNOSOMA. 
6. External ear opening none. : : : ; ; DOLIOSAURUS 
c. Infraorbital region with one long plates d. 
c. Infraorbital region with row of short plates or scales; occipital small. 4. 
d. Interorbital plates in two rows. : 5 ; 5 . : : AMA. 
d. Interorbitals in one or three series. e. 
é. Occipital the largest of the cephalic plates. f. 
é. Occipital plates no larger than the others. h. 
J. Caudal scales smooth; anterior limbs very long. g. 
f. Caudal scales above carinate; anterior limbs moderate. . . . Uta. 
Gi eHAarnaistinctw wens : Sead PETA F ° CALLISAURUS, 
g. Har invisible. A F : : ENC Re utile HOLBROOKIA. 
h. Rostral plate triangular; a row of scales like a crest extending along 
the back from nape to tip of tail. . . . . . DIPSOSAURUS. 
h. Rostraloblong; no trace of a dorsal crest. : . « CROTAPHYTUS. 
t Toes enlarged under the antepenultimate phalanges forming a suboval, 
transversely lamellate space. : : Samat 7 : .  ANOLIS. 
i. Toes not thus enlarged. 7. 
j. Tail blunt; rostral plate transversely cblong. : : . KUPHRYNE, 
j. ‘Tail pointed; rostral small, scale-like. . . 4 .  CROTAPHYTUS. 
GENUS SCELOPORUS. Wiegmann. 
Head short; cephalic plates smooth, the occipital largest ; a 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 without spines ; gular pouch 
not marked ; dorsal scales carinated, ventral smooth, imbricated ; tail long and pointed ; 
caudal and dorsa! crests wanting ; toes on each foot five, unguiculate; femoral region 
with a series of distinct pores. 
ScELOPORUS UNDULATUS Harlan. 
The Browm Swift. 
Lacerta undulata, DAUDIN. 
Uromastix undulata, MERREM. 
