510 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.54. 



Specimens examined. — Two left humeri and an imperfect left 

 innominate. 



Remarhs. — So far as can be judged from the structure of the 

 humerus Cyclura rriaUea is much more nearly related to Cyclura 

 cornuta and C. stejnegeri than it is to the G. pinguis of Anegada. 

 Doctor Barbour has kindly had the left humerus removed from the 

 type-specimen of C. pinguis and sent to me for comparison. It is 

 here figured on plate 81 (fig. 3). Though from an animal much 

 older than either of the specimens of C. mattea (figs. 4, 5), it is by 

 comparison decidedly small: total length, 61.5; greatest breadth of 

 proximal extremity, 23.7; greatest breadth of distal extremity, 21.5; 

 least width of shaft, 7 ; capitellum, 9.4 by 5.2. It agrees with the humeri 

 of G. mattea^ 6'. cornuta^ and G. stejnegeri in the general characters by 

 which the humerus of Gyclura differs from that of Iguana^ principal 

 among which are the great breadth of the extremities as compared 

 with the total length of the bone, and the presence of a well-defined 

 radial fossa. But it is immediately distinguishable by several de- 

 tails of form, notably by the shorter, broader general outline of the 

 expanded portion at each extremity. The length of the sharply de- 

 fined, ridge-like outer border of the bone in the region of the capitel- 

 lum and radial fossa is equal to half the width of the distal expan- 

 sion, while in both G. mattea^ G. cornuta., and G. stejnegeri it is con- 

 spicuously greater than half this width. As to the peculiarities of 

 Gyclura mattea as compared with G. cornuta and C. stejnegeri: the 

 remains appear to represent a much larger animal; the ratio of 

 greatest width of proximal expansion of humerus to the length of 

 the bone is 40 in G. mattea (paratype), 34.4 in G. stejnegeri (No. 

 29366), and 33.4 in G. cornuta (No. 28625) ; the same ratios for the 

 distal expansion are 36.7 (type), 31.9, and 33.4. 



The question naturally arises as to whether Gyclura mattea may 

 not have been brought to St. Thomas by man, as has undoubtedly 

 been the case with the species of Iguana now or recently living on 

 the island. There is, however, no such evidence for artificial intro- 

 duction as that presented by the rodent Isolohodon. The animal is 

 distinct from that of both Mona Island and Santo Domingo; the 

 humerus of the extinct Porto Eican member of the genus is not yet 

 known.^ 



CHELONIA MYDAS (Linnaeus). 



Shells and limbs of sea turtles of various ages and sizes are repre- 

 sented by about 40 fragments from St. Thomas and two dozen from 

 St. Croix. All the more complete bones appear to be referable to 

 Ghelonia mydas., though members of other marine genera may be 



1 Barbour, Proc. Biol. Soc. Washington, vol. 30, p. 98, May 23, 1917. 



