4 ARKIV FÖR ZOOLOGI. BAND 8. NIO 19. 



the small Peruvian Guanaco (fig. 1) than in the Patagonian 

 (fig. 2), but the distance between the bullse and the posterior 

 edge of lamince pterygoidece is greater in the former (conf. fig. 3), 

 than in the latter (conf. fig. 4). 



The two rather large foramina on the palate, which in the 

 Patagonian Guanaco are situated opposite p 3 or p 4 , and some- 

 times as far back as opposite m 1 (fig. 2), are in the small Peru- 

 vian Guanaco situated on the narrowed portion of the palate 

 considerably in front of p 3 (fig. 1). 



The upper brim of the orbit projects in the small Peru- 

 vian Guanaco more than the lower, so that it is visible from 

 below (conf. fig. 1), while the opposite takes place in the Pata- 

 gonian (fig. 2). 



In the Patagonian Guanaco the foramina incisiva extend 

 considerably in front of a line drawn across the palate on a 

 level with the anterior margin of i 3 (fig. 2), sometimes even 

 more than half of the foramina lie in front of such a line. In 

 the small Peruvian Guanaco the anterior ends of these fora- 

 mina lie behind the level of the front margin of i 3 (fig. 1). 



The molars of the small Peruvian Guanaco are (partly 

 even comparatively speaking) smaller than those of the Pata- 

 gonian, as the following measurements prove, which have been 

 taken from two specimens in the same stage of development 

 with the p 3 still in place. 



Peruvian Patagonian 



Length of m 1 16,5 mm. 21,5 mm. 



Transverse breadth of anterior lobe of m 1 . . . . 13,3 » 17,8 » 



Length of ra 2 19 » 25,5 » 



Transverse breadth of anterior lobe of m 2 .... 13 » 19 » 



Length of w 3 • 19 » 23 » 



Transverse breadth of anterior lobe of m 3 . ... 11,7 » 15,4 » 



On the other hand the lower incisors of the small Peruvian 

 Guanaco are very strongly developed so that, in spite of the 

 smaller size of the animal itself, the combined width of the 

 median pair of incisors is 16,5 mm., or exactly the same as in 

 two specimens of the much larger Patagonian Guanaco. In 

 a specimen from Tierra del Fuego these teeth are, however, 

 still broader (about 20 mm.). The molars of the lower jaw 

 are as those of the upper much smaller in the Peruvian Gua- 

 naco than in the Patagonian. If two specimens in which the 

 molars are worn to a corresponding degree are compared, the 



