548 University of California Publications in Geology [Vol.11 



PROBOSCIDEA 

 TETEABELODON 1, sp. 



A number of fragments of a large mastodontine form were 

 obtained in the Ricardo beds. 



A considerable portion of a lower jaw, no. 22681 (fig. 160), shows 

 the character of the lower molar teeth, and a portion of the sym- 

 physial region. The symphysis is elongated and the cross-section 

 of the lower tusk indicates that it was of considerable size. The 

 pattern of the lower cheek-teeth is that of an early Pliocene or late 

 Miocene type with comparatively simple outlines of the tubercles or 



162 



Figs. 161 and 162. Tetrabelodon?, sp. Lower cheek-teeth and incisor, X %. 

 Fig. 161, no. 22681; fig. 162, no. 21318. Eicardo Pliocene, Mohave Desert, Cali- 

 fornia. 



transverse ridges, but with secondary tubercles in the space between 

 the transverse ridges. A piece of an upper tusk shows a portion of 

 an enamel covering. A small lower incisor (no. 21318, fig. 162) has 

 a portion of the enamel band still intact. 



EQUIDAE 



The horse group is known in the Ricardo fauna by several clearly 

 marked species representing the genera Hipparion and Pliohippns. 

 The Ricardo horses are as a group much more advanced than the 

 Barstow species. A single Pliohippus-like specimen from Ricardo is 

 to be considered as possibly not more progressive than a relatively 



