486 



LAND MAMMALS IN THE WESTERN HEMISPHERE 



Deseado (also called the Pyrotherium Beds) was the latest, 

 largest and best known of the suborder. The dentition was 

 much reduced as is shown by the formula : if, c§, p |, to|,x2 

 = 28. The upper incisors were two downwardly directed 

 tusks, the first quite small, the second considerably larger; 

 the single lower incisor of each side was a stout, but not very 

 long, horizontally directed tusk, with the enamel confined to a 



Fig. 243. — Head of ]Pyrotherium, showing the two pairs of upper tusks. Restored 

 from a skull in the museum of Amherst College. 



longitudinal band ; the other incisors and the canines had dis- 

 appeared. The premolars, except the foremost one, had the 

 molar-pattern, which very rarely occurred among the indig- 

 enous South American ungulates. The grinding teeth were 

 similar above and below and each had two elevated, transverse 

 crests, which, when quite unworn, carried a row of bead-like 

 tubercles. These teeth are decidedly reminiscent of the den- 

 tition of the aberrant proboscidean \Dinotherium, from the 

 Miocene and Pliocene of Europe (p. 435), and this resemblance, 

 together with the form of the tusks, has led to the reference of 



