30 PROCEEDINGS OF THE NATIONAL MUSEUM vol.73 



No. 76, adult female. From Tres Marias, Nayarit, Mexico, by 

 M. Forrer. 



Diagnosis. — Dorsal crest very pronounced, not interrupted at sa- 

 crum, the continuity being effected by short lobes or depressed but 

 enlarged scales. Tail ringed on upper half with whorls of strong and 

 very spinous scales. First six >vhorls of spinous scales are separated 

 from each other by four rows of smaller flat scales; the next three 

 by three distinct rows and a partial fourth which borders the median 

 dorsal spines of the tail. Subsequent whorls up to half the length 

 of the tail are separated from each other by two rows of small 

 scales. Distal half of tail appears spinose throughout, the smaller 

 scales becoming larger and gradually pass into the spinous type. A 

 comparison of this species with its most nearly related species is 

 given under Ct. pedinata. 



Distribution. — This species is known only from Barranca Ibarra, 

 Jalisco, and Tres Marias, Nayarit. 



Description.— V .S.N .M. Nos. 18967, adult female type; 18970, half- 

 grown female paratype; Brit. Mus. Nat. Hist. Nos. 1, adult male; 

 75, adult male; 76, adult female, paratypes. Head long and narrow, 

 covered with small hexagonal scales and very distinctly marked off 

 from the body. Transverse gular fold present; no dewlap. Scales 

 on muzzle larger than other head scales. Nostrils large, situated in 

 the anterior third of the distance between orbit and tip of muzzle; 

 nostral equal in width to mental, and deeper; lores flat, supralabials, 

 12; sublabials, 13. The back and sides are covered with small, smooth, 

 subquadrate scales which pass graduafly into larger ventrals. Gular 

 region covered with small, smooth scales which become larger posteri- 

 orly. Smallest gulars as large as largest dorsals, but smaller than the 

 ventrals. Scales on limbs without spines. Tympanum nearly as large 

 as orbit. Supraoculars small, flat, and hexagonal, the externals being 

 about one-half as large as the internals, the internals being separated 

 from each other by four rows of scales. The dorsal crest begins imme- 

 diately back of the head and is composed of 73 compressed lobes, being 

 continuous with the caudal crest and not interrupted at the sacral region. 

 The lobes are highest (7 mm.) on the nape, and gradually diminish 

 in height posteriorly until on the sacral region, where they appear 

 merely as enlarged keeled scales. Their size and position makes them 

 conspicuous even in the sacral region. The dorsal crest is much 

 higher in males than in females. The tail is ringed about on the 

 upper half with whorls of strong and very spinous scales. These 

 whorls of spinous scales are separated from each other by rows of 

 smaller, flat scales, the first six by four distinct rows of small scales, 

 the sixth, seventh, and eighth by three distinct rows and a partial 



