146 Proceedings of the Biological Society of Washington. 



This form may be known as 



Cyclura portoricensis, sp. nov. 



Type, M. C. Z. No. 12,460, from the floor of the cave near Ciales, Porto 

 Rico, collected by Allen and Peters in February, 1917; being the extremi- 

 ties of a left humerus. 



Paratypes: A femur; tibia; two ulnae; a sacral and several dorsal verte- 

 brae; several incomplete mandibles; as well as a number of other bones less 

 perfect. 



The extremities of a fully adult humerus are chosen for the type for com- 

 parison with the type of Miller's C. mattea, also a left humerus. The two 

 species are evidently very closely related, more so with each other than 

 with other neighboring species of Cyclura, viz., pinguis of Anegada or 

 stejnegeri and cornuta. The species differs from mattea in being even 

 larger and more massive. (Cf. Miller, 1. c, pi. 81, fig. 4 and 5.) The bones 

 figured herewith are life size as are those figured by Miller. The greatest 

 diameter of the expanded proximal extremity of the type humerus (fig. G) 

 is 35 mm. In an adult Cuban Rock Iguana (C. macleayi) about three feet 

 long (M. C. Z. 6915 Santiago de Cuba; Col. Wirt Robinson, coll.) the same 

 dimension is 19 mm. 



U. S. N. M. 59,359, humerus, paratype of C. mattea, is before me and in 

 this example the distal expansion is 30 mm. and the proximal extremity 

 though broken appears to be correspondingly smaller and less massive. 

 The bicipital depression or radial fossa in mattea is very conspicuously 

 deeper and more extensive than in portoricensis; in this respect the latter 

 is even more like stejnegeri or cornuta than is mattea. This is what one 

 would expect from its geographic station. 



Portoricensis was so far as known the largest member of the entire 

 genus. 



I wish to thank Dr. Stejneger and Mr. Miller for permission to compare 

 the paratype of mattea with the material in hand. 



There is no reason to believe that man has played any part in the dis- 

 persal of Cyclura, as has beyond doubt been the case with the spreading 

 of Iguana through the Antilles. The distribution of Iguana is absolutely 

 haphazard, while that of Cyclura, as now definable, is typical of those forms 

 which spread by non-fortuitous or natural means. Cyclura undoubtedly 

 occurred in comparatively recent times on every suitable island which has 

 remained of the once more extensive Greater Antillean land. It is improba- 

 ble that this list of species with their habitats could be the result of chance 

 dispersal when it is considered that not one Cyclura is found elsewhere 



C. macleayi Gray, Cuba and surrounding Cayos. 



C. caymanensis Barbour and Noble, Cayman Islands. 



C. baeolopha Cope, Andros Isl., Bahamas. 



C. inornata Barbour and Noble, Exuma Keys, Bahamas (extinct?). 



C. rileyi Stejneger, Watlings Isl., Bahamas. 



C. nuchalis Barbour & Noble, Fortune Isl., Bahamas (extinct?). 



C. carinata Harlan, Turks and Caicos Isls., Bahamas. 



