No. 2328. PLEISTOCENE VERTEBRATES IN UNITED STATES— HAY. 139 



nearly complete. The length was originally a little more than 105 

 mm. and its thickness is 57 mm. If these teeth really belong to 

 E. columhi there is a great disparity in the sizes of the penultimate 

 milk molars of this species and E. prhnigenius, that of E. columhi 

 being about as large as the fourth milk molar of E. 'p^migenius. 



In the Iowa report referred to above ^ the writer described and 

 figured a lower penultimate milk tooth as belonging to E. colurnbi. 

 It had been found at Afton, Oklahoma, where both E. columhi and 

 E. impej'ator have been collected. The writer is now inclined to 

 regard the tooth as that of E. imperator^ partly on account of the 

 size of the tooth and partly because of the thickness of the plates 

 and of the enamel. It is a considerably larger tooth than the cor- 

 responding known teeth of E. columhi and far larger than that of 

 the teeth from Bulverde. 



As more than one other student of elephants, the writer has some- 

 times been tempted to set off from Elephas primigenius, as a distinct 

 species, the form that is found in the United States and southern 

 Canada; but each time that he has approached the subject he has 

 been arrested in the effort to find distinguishing characters. 



Two skull bones from Buherde are referred to the young of this 

 species, but it is possible that they belonged to the mastodon. Fig- 

 ure 1 of plate 10 (Cat. No. 9233) represents, of about one-half the 

 natural size, the left side of the basisphenoid bone. On each side is 

 a large air cavity, which opened below into the hinder end of the 

 nasal passage. Above this are seen openings into other air cells, 

 wholly within the body of the bone. Figure 2 of the same plate gives 

 a view of the inner surface of the right exoccipital (Cat. No. 9234). 

 Four openings to air cells in the bone are seen. 



There are present vaiious limb bones of two or more young pro- 

 boscideans, some of which are referred to the species here described. 

 Others are described above as those of a young mastodon. Among 

 these bones is the base of a left scapula showing the articular cavity. 

 There are also parts of three humeri, all with the epiphyses missing. 

 There appear to be differences among them, but the writer is not able 

 to determine their generic identity. 



A left tibia (Cat. No. 9235) of a young animal (pi. 10, fig. 7) 

 is referred to this species. It lacks both the epiphyses. The length, 

 taken in front, is 228 mm. The side-to-side diameter at the middle 

 of the length is 44 mm.; the fore-and-aft diameter, 41 mm. It is 

 thus shown to be a slenderer bone than that of Ma7nmut americanum 

 (pi. 10, fig. 8), as recorded under that species. A right tibia (Cat. 

 No. 9236) of a somewhat larger young elephant has lost the upper 

 epiphysis and a part of the lower end of the shaft. Still another 



ip. 413, pi. 61, figs. 7, 8. 



