m 



,., 



n 



440 



MONOOUAPIIS OF NORTH AMEltlOAN UODENTIA. 



Dr. Ely states that in the older niul larger American skulls, both orbital 

 processes are strongly developed, in many skulls the posterior one being us 

 strongly marked as in the European, a statement I find confirmed by my own 

 series. In the American skulls, he finds the position of the postorbital proc- 

 ess, in respect to the highest point of the malar bone, to l>e as stated by 

 Brandt, but records one exception to even this diflcrencc. 



"(3) The snout," says Brandt, "measured from the inferior orbital open- 

 ing to the inferior corner of the nostril in two European skulls of equal size 

 (Nos. TjC and liJG of the Kicw Coll.) is broader and somewhat longer than in 

 an American skull in the Academic Museum." 



"(4) The nasal bones," Brandt continues, "show the greatest variations. 

 Their lengtli in nil the European is much above one-third the' length of the 

 skull, measured from the incisor teeth to the crista occipitalis; while, on the 

 contrary, in the three larger of the American skulls the length of the nasal 

 bones is only a little if any over one-third, and the smallest not even one-third 

 the length of the skull. The nasal bones of the six older skulls lying before me 

 of the European Beaver arc therefore longer, and extend more or less far pos- 

 teriorly, i. e. more or less beyond the anterior prominence of the arch of the 

 eyebrows, so that they (the nasol bones) lie with their posterior borders 

 nearly or qnite opposite the middle of the margin of the orbits. In a young 

 Polish Beaver (No. 57 of the Kiew Coll.) they reach, however, only to the 

 anterior third of the orbital ring, and in our young Lapland Beaver they lie 

 nearly as in our California Beaver skull, opposite only the circumference of 

 the anterior border of the orbital ring. In none of five American skulls, 

 lying before me, on the contrary, do the nasal bones extend beyond the ante- 

 rior prominence of the eyebrows. In nearly all the skulls of the European 

 Beaver, compared with the five American ones lying before me, the nasal 

 bones are in form longer in the middle and posterior, however, in general nar- 

 rower, so that their breadth in their middle varies between one-fourth and 

 one-fiflh of their length, while in onr five American skulls the breadth of 

 their middle portion attains to between one-third and one-fourth of their 

 length. Although the nasal bones of the American beaver are thus on the 

 whole broader, still they vary less in this respect than in their lesser length. 

 The external border of the nasal bones of the European Beaver is not so 

 strongly curved as in the American. Two of the European skulls, however, 

 approach quite to the American in this respect. The superior surface of the 



