502 bulletin: musei'm of comparative zoology. 



l)reed. At first but a single specimen was found among numerous 

 other dog remains, but further search brought a few more to Hght, 

 and more recently the Yale-National Geographic Society P^xpedition 

 has recovered several skulls, from Huacho and Pachacamac. 



The presence of this pug-nosed doj* among the ancient Peruvians 

 is doubly interesting, not only in that this \ariation should have 

 occurred here, apparently cjuite independent of similar cases in the 

 Old World, but in that it should have been preserved, whether through 

 accident, or as supposed, through purposeful selection. Such a 

 shortening of the face through the imperfect development of the bones 

 of the rostrum is found occasionally in other domesticated manunals. 

 The short-faced Cheshire Hogs and similar l)reeds fiu'nisli like in- 

 stances of the selection and preservation of this mutation, which 

 appears to be definitely heritable. Among imdomesticated species, 

 the case of a European Fox is recorded by Donitz (1(S69) in which the 

 rostrum was shortened abnormally, producing a bull-dog-like appear- 

 ance, with undershot jaw. The second and third premolars of the 

 upper jaw were opposite the third and fourth respectively of the lower 

 jaw, while the upper canine fitted into a space between the first and 

 second lower premolars. Schmitt (1903) agrees with Studer (1901) 

 that such cases are due to the retention of embryonic conditions but 

 considers them to be a result of domestication. This, however, is 

 not necessarily the case, as the above instance shows. The case of a 

 "bull-dog-headed calf" is recorded by Warren (1910) as having ap- 

 peared as a " sport " \'ariation. 



Notwithstanding the comparatively high cultural development of 

 the Incas, it nuiy be doubted whether they purposely bred these dogs 

 for their peculiarity of face. Quite as likely the anomaly arose, 

 perhaps as a frequent result of cross-breeding between certain of the 

 other canine races, or as a local abnormality, which as a Mendelian 

 character, frequently cropped out in chance crosses. This may be 

 indicated by the apparent rarity of this type of dog in the Ancon 

 burials, and by the considerable variation in slight details of the form 

 of the skull, as if no special type were bred for. 



An interesting anomaly of an opposite nature is worth recording in 

 this connection, namely that of a Jackal shot by Dr. J. C. Phillips in 

 Arabia (M. C. Z. 15,872) in which the wider jaw has failed to reach 

 its normal length and is overshot by the upper jaw. The lower canine 

 closes hchind the upper instead of anterior to it as in normal cases. 



