652 REPTILES — IGUANID^. 



prottnsible ; maxillary teeth sometimes in a common alveolus, and sometimes soldered 

 tottejaw; gnlar region often provided with a ponoh; back sometimes crested; feet 

 four, with distinct toes ; premaxillary bone single ; mesosternum anchor- shaped. 



The Iguanidm are all extralimital except Sceloporus, but fhe following synopsis of those 

 inhabiting North America may be of service in referring the animals to their appropriate 

 genera : 



Dorsal scales oarinated ; infraorbital plate long. a. 

 Dorsal scales smooth or tuberculated ; nape without spine, v. 

 Dorsal region and nape more or less spinose ; body rauiform. 6. 



a. Cephalic plates smooth ; occipital as broad as long Sceloporus. 



a. Cephalic plates rugose ; occipital much longer than broad. . Halotrkpis. 



6. External ear opening present. Phrynosoma. 



6. External ear opening none. .... . . DoLieSAURUS 



0, Infraorbital region with one long plate, d. 



0. Infraorbital region with row of short plates or scales ; occipital small, i. 

 d, Interorbital plates in two rows. .... ... Ama. 



d, luterorbitals in one or three series, e. 

 e. Occipital the largest of the cephalic plates. /. 

 e. Occipital plates no larger than the others, ft. 

 /. Caudal scales smooth ; anterior limbs very long. g. 

 f. Caudal scales above carinate ; anterior limbs moderate. . . . Uta. 



g. Ear distinct Callisaurus. 



g. Ear invisible Holbrookia. 



h. Eostral plate triangular ; a row of scales like a crest extending along 



the back from nape to tip of tail Dipsosaurus. 



ft. Eostral oblong ; no trace of a dorsal crest. . . . CROTAPaYTCS. 

 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. 

 _;'. Tail pointed ; rostral small, scale-like Crotaphytus. 



Genus SCELOPOEUS. 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, which is 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 poach 

 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 Brovrn Swift. 



Lacerta undulata, Daudin. 

 Uromastix undulata, Mbrrem. 



