ART. 12 REVISION" OF LIZARDS OF GENUS CTENOSAURA BAILEY 43 



Type locality. — Restricted to Tehuantepec, Oaxaca, Mexico. 



Diagnosis. — Median dorsal crest made up of low, thin, leaflike 

 scales, extending from nape to sacrum. Upper surface of hind limbs 

 covered with large spinous scales. Upper surface of tail covered 

 with alternate rings of larger and smaller scales, the central, and 

 especially the two or three lateral series of larger scales, being very 

 large and heavily armed with a sharp spine directed backward. 

 Except at base of tail the larger scales forming the three series on 

 either side of the central caudal spines are flat. 



Distribution. — The type specimen of quinquecarinata is a stuffed 

 skin, in the British Museum of Natural History. It is without 

 any locality or collector's label. Of the 23 specimens examined, 

 19 are designated as being from Tehuantepec, Oaxaca, Mexico; 2 are 

 labeled merely "Mexico" ; 1 is listed from Oaxaca, Mexico. In all 

 probability all of the specimens came from Tehuantepec, at which 

 place the elevation ranges from 100 to 600 feet above sea level. This 

 species is perhaps confined to the Isthmus of Tehuantepec, and upon 

 the evidence presented above I hereby restrict the type locality of 

 Ctenosaura quinquecarinata to Tehuantepec, Oaxaca, Mexico. 



Description. — Brit. Mus. Nat. Hist. Nos. 61, adult male, type, 

 stuffed skin; 33, adult male, alcoholic specimen; U.S.N.M. Nos. 30127, 

 female; 30561, male; 30562, male; 30563, male. Head normal in 

 length, covered with small hexagonal scales, with slightly decurved 

 muzzle. Supraoculars very small, being separated from each other 

 by three rows of scales; nostrils large, on canthus rostralis, lateral; 

 loreal region smooth. Supralabials, 8; sublabials, 10; rostral wider 

 than mental; ear opening as large as orbit; strong transverse gular 

 fold; dorsal scales small and smooth, being almost granular on neck 

 and graduall}^ increasing in size posteriorly until over small of the 

 back. On the rump they become a little larger than ventrals, rhom- 

 boidal and obtusely keeled. Outer side of tibia armed with large 

 spinous scales. Dorso-nuchal crest made up of 50 to 60 thin, leaflike 

 scales ranging from 1 to 5 mm. in height, and extending from nape to 

 small of back (loins), or to sacrum, but never continuous over sacrum: 

 more pronounced in males than in females. Tail longer than head 

 and body together, slightly constricted at insertion; depressed in its 

 anterior third, but cylindrical posteriorly; its upper surface covered 

 with alternate whorls of larger and smaller scales; the central, and 

 especially the two (occasionally three) lateral series of the former, 

 very large and spinous; the latter and the three (occasionally four) 

 larger series adjacent to the central spinous row flat. First two or 

 three whorls of large scales at base of tail are all spinous. Lower 

 surface of tail covered with transverse series of smaller scales, strongly 

 keeled and pointed posteriorly. Femoral pores vary from 5-5 to 7-7. 



