ETNAU LÖNNBERG, SOME SOUTH AMERICAN CANID^. 13 



is triangulär, and in Ps. lycoides somewhat pentagonal, 

 although perhaps less so than in most other South American 

 Canidce. 



The dentition is different throughout. The Yaghan dog 

 has comparatively larger incisors; its canines are shorter and 

 stouter than in Ps. lycoides and rnagellanicus. In the Yaghan 

 dog p^ is provided with a small posterior cusp and in p^ 

 such a one is still better developed, while such cusps appear 

 to be missing in the Ps. magellanicus-gTou-p. The difference 



Fig. 3. Skull of the Yaghan dog seen from the side. 



in shape of the upper carnassial {p^) is very important, as 

 it seems. Its heel is much better developed in the Yaghan 

 dog, and it is directed inwards in such a way that it forms 

 a right angle against the longitudinal axis of the 

 tooth itself. The inner end of the heel comes thus rather 

 far behind the transversal line connecting the anterior ends 

 of p^ of both sides. The shape of m^ is also different as in 

 the Yaghan dog its longitudinal diameter is 78, i % of its 

 transverse diameter, while in Ps. lycoides the same percentage 

 is a little more than 68, and in Ps. rnagellanicus about 65 

 as far as my material admits any judgment. These relative 

 dimensions of m^ of the Yaghan dog agree thus much better 

 with the corresponding ones of Canis aureus viz. 74,4 — 80%, 



