NATURAL SCIENCES OP PHILADELPHIA. 181 



General form that ofA. maculatus. A strong nuchal fold in larger 

 specimens. Tail cylindrical or slightly compressed. Head elongate, muzzle 

 rather narrow, nostrils lateral. Canthus rostralis straight, loreal region long, 

 perpendicular. Occipital plate large, not in contact with superciliaries, in a 

 depression which is not defined in the young. Facial rugse not acute, con- 

 vergent anteriorly ; the enclosed depression elongate diamond-shaped, with 

 rather small, more or less keeled scales. Superciliary plates seven, in con- 

 tact or separated by one series of granules medially. Palpebrals numerous, 

 keeled. Loreal rows five or six. Upper and lower labials eight. Infralabials 

 small. Scales of the extremities small, keeled ; abdominal scales keeled ; 

 lateral scales minute, dorsal larger, keeled ; two median rows abruptly largest. 

 Auricular opening moderate, vertical. Digital expansions moderate ; second 

 and fifth fingers nearly equal ; anterior extremity reaches groin ; posterior, 

 middle or anterior part of orbit. 



General color darker or lighter brownish green, the extremities faintly 

 banded. A few dorsal dots in the young. 



Habitat. Nicaragua. Mr. C. Wright, of Capt. Rodger's Exped., collection 

 Mus. Smithsonian (No. 6055); Phila. Academy. 



The young of this species may be distinguished from A. cupreus Hallow, 

 by the longer muzzle, more prominent facial rugse and nearer approach of the 

 superciliary plates ; from radulinus by the same characters, and by the 

 greater size of the interrugal scales and the coloration. A. cupreus Hallow, 

 is nearly related to A. cooperi Baird, both differing from A. s a 1 1 a e i in the 

 the less number and uniformity of the rows of keeled dorsal scales. In 

 cooperi the first infralabial is large as in sagrae, and there is a strong 

 prebrachial fold. The palpebrals are three or four-rowed. In cupreus 

 these are only two rowed, and the infralabials are small. The colors are 

 lighter. 



A. longicaudus Hallowell, described in the memoir referred to at the 

 head of the description of this species, is allied to A. tropidogaster Hallow. 

 Like it, it is a slender animal, the length from the muzzle to the tympanum 

 entering two and a half times into the distance from the latter point to the 

 groin. The tympanum is, however, very much smaller, the dorsal scales are 

 larger and the facial ruga? more strongly pronounced. The head is narrower. 

 Dracontura bivittata, described in the same memoir, belongs to the sub- 

 family of Basiliscina?, where it should be placed next to Thysanodactylus Gray. 

 In proof of this, it may be stated that the external nares are lateral, and the 

 toes broadly margined. From all the genera it differs in its plain occiput, 

 without enlargement or compression, and the total absence of nuchal, dorsal 

 or caiidal crest. Tail compressed. A transverse gular fold. The species may 

 be called Paraloma bivittata. 



Basiliscus (Cristasaura) n u c h a 1 i s. 



Tail compressed, its superior margin undulate serrate. Dorsal crest low, 

 extending between interscapular and crural regions ; its rays eleven. Helmet 

 highly developed, produced posteriorly, where its outline is sigmoid ; from 

 its posterior extremity to its anterior, which is between the hinder borders of 

 orbits, its margin is more than twice as long as from the last-mentioned posi- 

 tion to the end of the muzzle. It is thin and covered with smooth scales, 

 which are much larger than any on the cranium. Occiput much swollen, its 

 scales smooth ; supraorbital scales keeled. Superciliaries ten on each side, 

 separated by three rows of scales. Facial ruga) well developed, enclosing a 

 concavity covered with rough scales. Muzzle scales scarcely keeled. Canthus 

 rostralis acute. Rostral bordered by three plates posteriorly. Labials seven 

 or eight above, nine below. Tympanum half as large as bony orbit. Two 

 gular folds. Abdominal scales keeled. Dorsal flat, subquadrangular, slightly 

 keeled, larger than lateral. Hinder extremity extends beyond the muzzle. 



1862] 



