296 PATAGONIAN EXPEDITIONS : PAL/EONTOLOGY. 



SCHISMOTHERIUM FRACTUM AmeghinO. 

 (Plates L; LI, Figs, i, 4, 4*1; LIII, Figs, i, 8.) 



Schismotherium fractum Amegh. ; Enumeracion sistematica, etc.; 1887, 

 p. 21. 



In the Princeton Museum this species is represented by two skulls (Nos. 

 15,344, 15,524), a mandible without teeth (No. 15, 361) and by a leftramus 

 mandibuli, with the teeth in place (No. 15,901), all of which were obtained 

 by Messrs. Hatcher and Peterson at Killik Aike. In addition to this there 

 is in the Ameghino collection a fine skull, with mandible and fore-limb 

 nearly complete, while the type-specimen in the La Plata Museum is suffi- 

 ciently characteristic for the satisfactory identification of other specimens. 



In both upper and lower jaws the teeth form almost continuous series, 

 though short interspaces divide them, slightly longer between - and - ; - is 

 quite small, caniniform, laterally compressed and narrow, plane on the 

 inner and convex on the outer side and with obliquely truncate masticat- 

 ing surface ; - has the styliform character which is so constant in all this 

 group of genera ; in the present species it is usually subcylindrical or 

 slightly oval, with principal diameter antero-posterior ; -, the largest of 

 the series, is transversely oval ; - and - 1 , also oval, diminish successively 

 in size. In the mandible T approximates an equilateral triangle in section, 

 but is sometimes very small and subcylindrical ; ? and * are transversely 

 elliptical and of nearly equal size, and * is usually cylindrical, but may be 

 oval like ^, though always less compressed antero-posteriorly. 



MEASUREMENTS. 



No. 15,3^4. No - i5,5 2 4- 



Upper dentition, length 039 



" " A-A 031 .031 



-L, length (/'. e., antero-posterior diameter) 007 



" width (i. e., transverse diameter) 005 



, length 008 .008 



" width 007 .007 



S-, length 009 .006 



" width 01 1 .01 1 



4 , length 006 .006 



" width 009 .010 



*-, length 006 -0055 



" width 007 .008 



