438 AXXAL8 XEW YORK ACADE2IY OF SCIEXCES 



The fish remains have been identified by Dr. L. Hussakof. Curator of 

 Ichth^'Ology, American Mnseiun of Xatural History. 



Dr. Allen said in abstract: During the exploration of a cave in the 

 Jobo district, near Utuado. Porto Eico, made under the direction of Dr. 

 Boas, several hundred mammal bones were obtained, all referable to a 

 single species of an extinct octodont rodent. These bones are well pre- 

 served and have the character and general appearance of recent bones. 

 They include several nearly complete skulls, a large number of mandib- 

 ular rami, a pelvis and many limb bones and ribs. They represent a 

 species about the size of Plagiodontia and the smaller species of C a pro my s, 

 but it is not closely related to either of these genera, nor to any other 

 known genus. It is especially characterized hj the enamel pattern of the 

 molariform teeth, which is strikingly different from that of any other 

 described octodont. In size, in the general form and proportions of the 

 skull and in the oblique insertion of the grinding teeth, it resembles 

 Plagiodontia,, known thus far only from the type specimen from Haiti, 

 described by F. Cuvier in 1836 and now probably extinct. 



In both Plagiodontia and the new form from Porto Pico, which may 

 be known as Isolohodon portoricensls, the transverse axis of the molars 

 is highly oblique to the axis of the tooth-row, the obliquity of the two 

 axes being about 45°, instead of the two axes forming a right angle, as 

 in Capromijs. The molariform teeth in Isolohodon resemble those of 

 Plagiodontia not only in manner of insertion, but in size and form and 

 in the number of enamel folds on the outer and inner borders. They 

 radically differ from those of Plagiodontia in the enamel pattern of the 

 crowns, in which latter the cement area of each tooth consists of three 

 transverse divisions, united and continuous, thus constituting a single 

 sigmoid area, deeply cut by the infolding of the enamel border. In 

 Isolohodon the cemented portion of the crown surface of each upper molar 

 forms two transverse, nearly equal oval areas, each entirely encircled by 

 its own enamel border. The enamel pattern of the lower molars differs 

 from that of the upper molars through the deep indentation of the ante- 

 rior enamel area by the infolding of the enamel border on the inner side 

 of the front third of the tooth. 



The condition of the remains of Isolohodon indicates its recent extinc- 

 tion, they having undergone no change in mineralization or even in 

 coloration. As in the case of Plagiodontia, it was probably extermiuMted 

 by the natives, who doubtless persistently hunted it for food, as its flesh 

 must have been highly palatable and as it was the largest indigenous 

 mammal of the island. It is known that this fate overtook Plagiodontia 

 at about the middle of the last centurv. as Cuvier states that it was 



