294 APPENDICES. 



I find American skulls in which the upper surface of the lachry- 

 mal bone has the quadrangular form, as broad anteriorly as pos- 

 teriorly, and united as in the European skull, to the intermaxillary, 

 while in the greater number of instances the description above 

 given is found to be correct. 



" § 2. Anterior aspect of the skull. 



" On the closer study of the beaver skull anteriorly, we learned 

 that in all the examined skulls of the European beaver the nasal 

 opening appears triangular, inferiorly narrow, and hence more or 

 less pointed; while the lateral margins, raised like a crest, and 

 bounding it inferiorly, approached each other at a more or less 

 acute angle. In the American skulls, on the contrary, the nasal 

 opening has a quadrangular form, and appears below only a little 

 narrower than above; while the lower ends of the crest-like ridges 

 of the lateral margins are nearly parallel, and curved inward but 

 little." 



The tendency to the quadrangular form of the nasal opening 

 in the American beaver, and to the triangular form of the Euro- 

 pean, is evident. Yet there are American skulls where the form 

 of the opening is nearly if not quite as triangular as in the Euro- 

 pean. 



"A comparison of the both equally large European skulls with 

 the American skull of equal size of the Kuprianow skeleton, 

 showed that the inter- and inferior maxillary, together with the 

 incisor teeth, are strikingly broader iu the European, but some- 

 what lower than in the American skull. So much so indeed that 

 the br'^adth of the American intermaxillary is to that of the Eu- 

 ropean as 9 : 13, nearly as 3 : 4. The breadth of a single inci- 

 sor tooth of the upper jaw in the European beaver is something 

 more than one-third the breadth of the anterior inferior border of 

 the intermaxillary, while each single upper incisor of the American 

 beaver is equivalent in breadth to one-third the transverse di- 

 ameter of the inferior border of the intermaxillary." 



In the measurement of five skulls I find the breadth across the 

 incisor portion of the intermaxillary to average 88"', and the 

 average width of a single upper incisor to be 3Q'". In five other 

 skulls the intermaxillary width is 18'", and the width of an inci- 

 sor is 27'". In another skull the intermaxillary width is 91'", 

 and the width of the incisor is 32'". This is "something more 

 than one-third." 



