Cope.] 264 fOct. 16, 



to the tridentate form of the C. milila. The character is, I think, even 

 if constant, insufficient for generic distinction. 



I describe the two specimens -which represent the extreme of variation 

 of this species, commencing with the type of C. nigerrima. 



In this specimen the scales of the superior regions are smaller than 

 those of the inferior regions, and are in regular transverse rows, each 

 scale surrounded with granules. There are three rows in two millimeters. 

 The scales of the inferior surfaces are about a millimeter in diameter ; like 

 those of the back they have faint traces of keels. The scales of the limbs 

 and tail are keeled. At intervals of about six scales, there are, on the 

 median portions of the sides of the tail, two rows of scales a little larger 

 than the others, which are homologous with those which form the spiny 

 whorls in other species. The crest is rather low on the nape, and is well 

 developed on the dorsal region and anterior part of the tail. On the latter 

 it becomes lower, forming serrate teeth, which are distinguishable to the 

 end of that organ. The crest is interrupted at both withers and rump. 

 Besides the combs on the second and third digits, there is a rudiment of a 

 comb at the base of the first digit. Femoral pores 14-16. 



The type specimen of this species was partially skeletonized before it 

 was suspected to be other than a Metopocerus cornutus. The plates and 

 scales of the head cannot therefore be described excepting so far as to 

 state that there is a median large scale at the middle of the base of the 

 snout, on an elevation of the nasal bones just behind the transverse line 

 connecting the posterior borders of the bony nares. Between this plate 

 and the canthus rostralis the horizontal surface of the muzzle is covered 

 with rather large anteroposterior^ oval scales, which have a median keel. 

 In the center of these is a larger plate, several times as large as any ot 

 them. The scales on the post-frontal region are similar and those of the 

 zygomatic arch posteriorly are larger. 



j icaaurements. M. 



Length of skull to end of quadrate bone 108 



Width of skull at front of tympanum 070 



Least interorbital width of skull 018 



Length of alveolar edge of maxillary bone 050 



" " body to vent 340 



" tail 500 



" "humerus 0G0 



" " fore arm 0.~>7 



" "femur 07."> 



"tibia 063 



" foot 110 



The color is everywhere uniform black. 



From Navassa island. National .Museum, No. 9974. 



In a second specimen, the type of Gyclura onchiopsis, the scales of the 



