16 MEMOIR ON THE III. 



breadth between them, and adds that it would be difficult to distinguish this cra- 

 nium from that of the recent Musk Ox. 



Of the specimen described by Ozeretskovsky, Cuvier is undecided whether to 

 consider it as belonging to the same species of the latter or not, but a simple in- 

 spection of Ozeretskovsky's figures, reproduced in Cuvier (Plate CLXXIL, Figs. 

 6 and 7), proves a very close relationship with the recent Musk Ox, and indicates 

 a very distinct animal from Bootlierium cavifrons, as represented in the figures 

 of the cranium, in Plates III., IV. of this memoir. At a glance, it will be ob- 

 served that in the former, the horn-cores approach very near each other along 

 their bases, and turn up at their tips like in the Musk Ox, while in the latter, 

 the horn-cores are widely separated at base, and do not turn up at the tip. 



Among a large collection of bones and teeth of the Mastodon from Benton 

 County, Missouri, purchased by the American Philosophical Society, and deposited 

 in the Academy of Natural Sciences, I have observed the cranial portion proper of 

 the head of three individuals of Bootherium cavifrons, agreeing in all the details 

 with the specimen just described. With them, also, there are fragments of five 

 horn-cores of the same species. 



All these Missouri specimens are much decomposed, being exceedingly friable, 

 white, and chalk-like. They are much mutilated, but all the cranial fragments 

 still possess the remains of the remarkable frontal process, and, in one specimen, 

 this verges close upon the inion, and in that position is two and a half inches in 

 thickness. 



In the collection of the Boston Natural History Society, I observed a specimen 

 consisting of the posterior part of the cranium with portions of both horn-cores of 

 Bootherium cavifrons, which was discovered in the alluvium of the Kentucky 

 Eiver, a tributary of the Ohio River, in Kentucky, and was deposited with the So- 

 ciety by Mr. J. W. Foster. 



Through the kindness of Professor Baird, I have received, for inspection, from 

 Professor Samuel St. John, of Hudson, Ohio, a much water-worn fragment of a 

 cranium with one horn-core attached, of the same species, which was found in 

 Trumbull County, Ohio. 



Thus have been indicated portions of the crania, of at least twelve individuals of 

 Bootherium cavifrons, all found in the great valley through which flows the Missis- 

 sippi with its tributaries. And from the number of remains, it is probable that 

 this animal, at a former period, fed in vast flocks upon the rich prairies of the val- 

 ley and the fertile banks of its streams. 



Accompanying the fragments of crania and horn-cores of Boolherium cavifrons, 

 from Missouri, above described, were two astragali and a metacarpal bone in the 

 same condition of preservation as the former specimens, and no doubt belonging to 

 the same animal. 



The astragali have their surface much disintegrated, and, in their present state, 

 measure about three and a quarter inches in their long diameter, and two inches in 

 their breadth. 



The metacarpal bone is also much injured upon the surface. 



Its measurements are as follow : 



