R. 8. Lull — Fauna of the Dallas Sand Pits. 161 



together with their being directed downward and for- 

 ward so that the auricular fossa is nearly closed below, 

 whereas in Felis it is wide open and the vertical extent 

 of the mastoids is relatively slight. The occipital 

 condyles are also SmilodonASkQ and show a great habit- 

 ual range of vertical movement than in Felis. All this 

 is correlated with the great development of the sterno- 

 mastoid muscle in Smilodon for use in striking its prey, 

 and is highly diagnostic of the genus. 



Fig. l.—Smilodon cf. fatalis (Leidy). Cat. No. 1.52, S. M.U. Oblique 

 aspect of cranium. X "V^* 



But one species of Smilodon has been described from 

 Texas, S. (Trucifelis) fatalis (Leidy)^, of which the type 

 consists of a single upper carnassial with a small portion 

 of the maxillary attached. As this element is unrepre- 

 sented in the present specimen, comparison was made 

 with a fine skull of S. calif or nicus from the Rancho La 

 Brea asphalt. Cat. No. 10204, Y. P. M., and the com- 

 parable ratios between that and Leidy 's type on the one 

 hand, and the Dallas * specimen on the other, exhibit 

 a close agreement, as the table of measurements shows. 



"Joseph Leidj, Jour. Acad, Nat. Sci., Phila. (2), 7, 366, pi. 28, figs. 10, 

 11, 1869. 



Am. Jour. Sci.— Fifth Series, Vol. IT, No. 9.— September, 1921. 

 11 



