48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



have been compared by Dr. J. A. Allen with extensive material from 

 South and Central America ; and it is Dr. Allen's opinion that they 

 are best referred to this form, though they do not represent it in its 

 extremes." Later studies have led to the recognition of these as 

 representing an insular race with less blackish face and skull char- 

 acterized by relatively broader rostrum, narrower braincase and 

 posteriorly expanded zyzomata in comparison with the form inhabit- 

 ing the adjacent mainland. 



Specimens examined : San Miguel Island, 2. 1 



DIDELPHIS MARSUPIALIS BATTYI Thomas 



Batty's Opossum 



Didelphis marsupialis battyi Thomas, Novitates Zoological, Vol. 9, p. 137, 

 April, 1902. Type from Coiba Island, Panama. 



Batty's opossum is described as a rather small dark-faced insular 

 race. It was originally compared with D. in, caucce of Colombia, but 

 is probably most nearly allied to the form inhabiting the adjacent 

 mainland. 



Allen (1902, p. 264) in his review of the group, after quoting the 

 original description, says, " D. m. battyi seems to represent a small 

 insular race, as shown by several topotypes kindly presented by the 

 collector, Mr. J. H. Batty, to this Museum. I am also indebted to 

 Mr. Batty's kindness for a transcript from his note-book of the 

 measurements of the specimens taken before skinning. I am thus 

 able to supplement Mr. Thomas's description with the flesh measure- 

 ments of not only his type, but also of seven additional specimens. 

 .... The four females, rather strangely, happen to range rather 

 larger than the four males, doubtless owing to the fact that the 

 females had reached a greater maturity than the males. If the 

 females of the Coiba Island series and the females of the Boqueron 

 and Boquete series [referred by him to D. m. etensis'] be taken 

 as the basis of comparison, the apparent difference in size prac- 

 tically vanishes." Specimens examined by me are somewhat darker 

 on the face than etensis as represented at Boqueron on the adjacent 

 mainland. 



Specimens examined : Coiba Island, 3. 



Genus MARMOSA Gray 

 The genus Marmosa includes a number of small, slender, long- 

 tailed species commonly termed " Murine " opossums, owing to a 

 very superficial resemblance to rats. They are rat-like, however, 



1 Specimens in Mus. Comp. Zool. 



