140 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
GENERAL CONSIDERATIONS. 
The members of the genus Cyclura form a small compact group of 
species confined to the Greater Antillean district of the West Indian 
region. Related to the Rock Iguanas (Ctenosaura) of the Central 
American mainland they are nevertheless well set off from the latter 
by the possession of the peculiar corneous combs or pectinations on 
the hind toes. Except for this character common to all the West 
Indian forms, some of these would appear more closely related to 
some race of Ctenosaura than to another of the island species. On the 
whole, it does not seem advisable to recognize the genus Metapoceras 
for the so-called Rhinoceros Iguanas of Navassa, Haiti, and Mona, 
since they are obviously but slightly advanced modifications of such 
a type as the Jamaican Iguana, which is a true, and probably an- 
cestral, Cyclura in every respect. The species in the Cayman 
Islands is nearly related to the Cuban, and the number of forms 
known from the Bahamas represent two groups of species, one showing 
affinities with the Cuban, Cyclura macleayi. In the Bahamas, baeo- 
lopha of Andros Island seems most like macleayi, with its neighbor, 
inornata, hardly less similar; while nuchalis of Fortune, rileyi of 
Watlings, and carinata from Turks Island form another well differ- 
entiated group of races. The latter species has head-scales of a 
simple and scarcely modified, one might, at first sight, say obviously 
primitive nature. We imagine, however, that this condition has 
been reached secondarily, the transition back through some of the 
other species being clearly traceable. So that while the scales of the 
head of carinata are of a very simple and undifferentiated character, 
it is nevertheless extremely improbable, especially in view of its habi- 
tat, that the species can be considered ancestral or anything more 
than a reversion to the probably, or possibly, primitive condition for 
Cyclura, and Ctenosaura, or their progenitors. It does not seem 
wise to lay much stress upon the distribution of the species of Cyclura 
as a basis for any zoégraphic deduction or surmise. We know but 
little of the habits of the species, the whole group is fast disappearing 
and will soon be wholly extinct, and even now we are able to character- 
ize but eleven species, probably a comparatively small part of those 
in existence even two hundred years ago. 
Early writers often mention Iguanas in the West Indies, and of 
these some referred to the genus Iguana and some to Cyclura; among 
the latter was Catesby. This authority writing upon the Natural 
