TEIID LIZAEDS OF THE GEXUS CNEMIDOPnOKUS 55 



catus, and its lonoitudinal rows of ventral plates are reduced to 

 eioht. from the 10 to 12 ventralled condition of murinus^ as are those 

 of all of the remaininf^ species of C nemidophonis. The range in 

 the number of femoral pores for mu7'inus has been found to be from 

 27 to 45, for aruhensls 27 to 33. and for Jemniscatus from 15 to 29; 

 thus, again, anibensis is transitional. The pattern of murinus con- 

 sists essentially of a uniform dorsal ground color, broken only by 

 large, round, white spots on the sides, although a few young speci- 

 mens from Curasao, which is geographically adjacent to Aruba, 

 show the suppression of lateral spots and the assumption of more or 

 less distinct dorsal stripes as do juveniles of amhcnsis. This process 

 proceeds so far in a/'uhcnsis that the adult females are often found 

 with stripes and from these to the perfectly striped young of lemnis- 

 catus is but a step. The latter form often reverts to the spotted, 

 unlined, condition in the adult male, developing enlarged blue spots 

 of the sides and at times approaching adult anibensis in general 

 appearance. Also, the largest adults of Jemniscatus are smaller than 

 adults of aimhensis and murlmus, and the additional derivatives, 

 ■nigricolor and ocellifci\ are even smaller than specimens of 

 lonniscatus. 



Lemniscatus is central in relation to the other forms of its group 

 and, as a wide-ranging, plastic entity, has had ample opportunity to 

 give rise to other forms. It is found from Guatemala in the north 

 to northern Brazil in the south. In Brazil its stock has evidently 

 given rise to ocelIifej\ which has been rendered very distinct by a 

 marked reduction in the number of femoral pores. These openings 

 have changed from a minimum of 15 in Jemniscatus to a maximum 

 of 12 in oceJlifer. The supraocular granules are also modified in 

 ocellifer, extending much farther forward than in Jemniscatus. 



In the island arc just north of Venezuela, extending from Aves 

 Island just east of Bonaire to Margarita Island, nigricoJor has pre- 

 sumably risen from Jemniscatus, possibly being derived after isola- 

 tion by partial submergence of the general area. Subsequent sub- 

 mergence has then, perhaps, isolated the modern island populations 

 of nigricoJor from each other. The transition from Jemniscatus to 

 nigricoJor is still shown by intermediate specimens on Margarita 

 Island which tend to lose all stripes at a very early age and to have 

 the rounded spots on the sides reduced in size. With the exception 

 of an average diminution in the keeling of the subcaudal scales in 

 nigricoJor, the form is structurally practicall}^ identical with 

 Jemniscatus. 



It may be said here tliat the break in relationships shown between 

 the lizards on Bonaire {murinuf<) and Aves Islands {nigricoJor), 

 whose habitats are geographically adjacent, may be due to an 

 ancient rift between these two points. 



