384 



F. B. Looinis — JS'ew Genus of Peccaries. 



From the above it will be seen that the various genera of 

 peccaries represent three lines of development, a mesocephalic 

 type beii;iunini>; with ]^er('ho?rus and ending in Tayassu, a doli- 

 cocephalic type including Prosthennops and Myloliyus, and the 

 aberrant genus of Platigonus. The series is distinctly an 

 American one, appearing first and doubtless by migration from 

 Asia during the lower Oligocene. A couple of species have 

 been doubtfully referred to Hyotherinm, and it was probably 

 some primitive member of that genus which on reaching this 

 side soon developed the peculiarities which separate the pecca- 

 ries from the pigs. Life in a more open country might well 

 have started the modifications which are especially along the 

 line of slenderer build and speed. The following diagram 

 may grapiiically iudicate the general relationships of the 

 known genera : ' 



Recent 



Tayassu 



Pleistocene 



Mylohyus 



Platigor^us 



Pliocene 



Platigonus 



Up. Miocene 



Prosthennops 

 / 



Platigonus 



Mid. Miocene 



Pediohyus 



Low. Miocene 



Desmathyus 



Up. Oligocene 



Bothrolabis 



Mid. Oligocene 



Perchoerus 



Beside these thei'e are a few forms known only by fragmen- 

 tary material, like Chsenohyus, Leptochoerus, and Nanohyus, 

 which cannot be placed in their relationships until more com- 

 plete material is found. 



Amherst College. 



