CONTENTS OF A BONE CAVE. 9 



phous characters. The inferior incisive alveolus does not project on the inner side 

 of the ramus, and the angle is a continuation of the general plane which incloses 

 the alveolus. The ascending ramus is much more elevated, rising abruptly from 

 the horizontal ramus. The symphysis is short, and, like the beaver, was not proba- 

 bly invested by the hairy skin as in the Chinchilla and AmllyrJiiza. 



Hintory. The first notice of this genus was published by the writer in the Pro- 

 ceedings of the Philadelphia Academy for 1868, p. 313, in the following language. 

 Prof. Cope . . . also exhibited bones and teeth of a large rodent from the cave 

 deposits of Anguilla, one of the Virgin West India Islands. The characters ob- 

 served were those of the genus Chinchilla, but the roots of the teeth were contracted 

 and not so open as in many rodents, as though having a more limited period of 

 growth, or perhaps like deciduous teeth, which are much reduced in number in 

 most rodents. The species was nearly as large as the Castoroides ohioensis of 

 North America, but had relatively smaller incisor teeth. The body was probably 

 as large as that of the Virginia deer, and the limb bones as stout, as seen in por- 

 tions of femora and other pieces preserved. He called the animal Amblyrhiza in- 

 iiudata, and thought that its discovery on so small an island, with others of like 

 character, indicated that the Caribbean continent had not been submerged prior 

 to the close of the Post-pliocene, and that its connection was with other Antilles, 

 while a wide strait separated it from the then comparatively remote shores of 

 North America. 



Subsequently in the Proceedings of the American Philosophical Society-for 1869, 

 p. 183, I more fully defined the genus from more complete material received from 

 Dr. van llijgersma. I at the same time described the inferior molars, but on ac- 

 count of the great difference which they display as compared with the superior 

 molars, I did not suspect that they belonged to the same genus and species as the 

 latter. I then gave them other names, generic and specific, which are now with- 

 drawn. In the same periodical for 1870, p. 608, I added the species A. latidens, 

 and in the same of the following year (p. 102) I added some observations on the 

 geographical relations of the genus, and described the species A. quadrans. 



AMBLYRHIZA INUNDATA, Cope. 



Proceedings of the American Philosophical Society, 18C9, p. 183. Loxomylus longidens, Cope, 

 loc. cit. 1869, p. 18G. Plates IV. and V., figs. 1-3. 



The remains of this large rodent were found in a mass of breccia, which was 

 thrown out in the excavations made in a cavern in the Virgin Island of St. 

 Martins, W. I. The remains, occurring in that most eastern region of the West 

 Indian Zoological district, might be anticipated to have a special interest in connec- 

 tion with the history of the submergence of a once great continent. With this 

 impression, the writer examined a quantity of the above breccia and cave deposit, 

 which was brought to Philadelphia as a probably available phosphatic manure. 

 It was found to be valueless for this purpose, and the only result of the outlay was 

 the discovery of the subjects of the present memoir. Most of the fragments first 

 described were dressed from a single block. There were in this, the extremity of 



2 April, 1883. 



