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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 73 



smaller than those on muzzle; nostrils large, very near tip of snout, 

 almost tubular, opening obliquely backward; lores flat; 9-11 enlarged 

 supralabials; 8-10 enlarged sublabials. Dorsal scales small, hardly 

 more than half size of ventral scales, gradually increasing in size poste- 

 riorly, smooth; a well-developed dorsal crest composed of from 65-80 

 carinated scales, beginning just back of head, on neck, and continuing, 

 uninterrupted, to sacrum; in large, old males these spines are cone- 

 like and often reach a height of 8-15 mm. Dorsal crest and caudal 

 crest entirely separate, there being no indication of crest in sacral 

 region. No spines on any scales of fore or hind limbs; femoral pores 

 vary from 4-4 to 9-9. Tail slightly constricted at insertion, rounded 

 posteriorly, at least twice as long as body in unmutilated specimens; 

 caudal scales above and laterally, in whorls, large, spinous; whorls 

 separated by smaller flat scales, of which the median dorsal are spi- 

 nous throughout length of tail; first and second or first, second, and 

 third whorls of spinous scales separated by 3 rows of small flat basal 

 scales; next 10 or 12 whorls of spinous scales separated by 2 rows of 

 small flat scales; other whorls separated by only 1 row of flat scales, 

 which about middle of tafl, also become spinous, thereby giving distal 

 half of tail a spiny appearance throughout. At base of tail, ventral 

 scales much smaller, three rows corresponding to each pair above, 

 slightly keeled and pointed posteriorly. After first 3 or 4 rows 

 ventrals and dorsals approach each other in size, 2 rows of ventrals 

 corresponding to a like number of dorsals. Toes rather long, espe- 

 cially those of hind feet; claws strong and sharp. 

 Measurements. — 



Coloration. — Adult: Head, neck, body, tail, and limbs dull brown- 

 ish above; under parts lighter with somewhat indistinct clouds and 

 marblings of a whitish cast. On belly and sides are three or four 

 bands of faded slate or bluish green which extend up and across back, 

 being hardly visible except where dorsal crest spines are involved. 

 A few very large males exhibit blotches of rusty red or cinnamon 

 over body, especially on sides and shoulders. Large adults of this 

 species are often referred to as "Black Ctenosaurs." 



It seems that dried skins lose most of their color, so great weight 

 should not be given to descriptions made from such specimens. 



