296 APPENDICES. 



"5. The ridge formed by the parietal and frontal, behind and 

 below the posterior tubercle of the eyebrow arches, in the Eu- 

 ropean skull, is more considerable, and enters into combination 

 with a ridge elevating* itself out of the squamous portion of the 

 temporal, which ridge in the American is generally wanting, or 

 only indicated." 



Brandt's largest American skull was but a medium sized one, 

 measuring 5" 24"' by 3" 60'". In an American skull of this 

 size before me the ridges in question exist; but in the older and 

 larger skulls they are strongly developed, 



" 6. The hook-formed process of the zygomatic process of the 

 temporal bone lies with its anterior point, in the American beaver, 

 hardly or only a little behind the anterior border of the temporal 

 fossa, while in the European beaver it always lies more or less 

 behind it. In the European beaver the end of the zygomatic 

 process of the temporal bone appears on the whole more ap- 

 proached to the occiput and osseous auditory meatus." 



According to my own observation, the hook-formed process 

 referred to above is in the American beaver longer than in the 

 European. We have but one or two skulls in which it appears 

 somewhat shortened, without becoming as short as in the Eu- 

 ropean variety. With respect to the relations of the zygomatic 

 process and the auditory tube, the American skulls are variable, 

 and strong resemblances could undoubtedly be found to the Eu- 

 ropean form. 



"7. In the American beaver there extends downward from 

 the posterior angle of the posterior end of the parietal bone a 

 more or less triangular, somewhat cuiwed process, which pro- 

 ceeds between the posterior crucial process of the squamous por- 

 tion of the temporal bone and the squamous portion of the occip- 

 ital bone. In consequence of this but slightly indicated process 

 in many European beavers, as in our Rolaer, the posterior and 

 upper angle of the squamous portion of the temporal bone of the 

 American beaver is generally more rounded, but in the European, 

 triangular and shorter." 



I have found but a single and partial exception to the above 

 statement. In an American skull. No. 2031, S. I., there is an 

 exact correspondence between the above-described processes and 

 those of the European beaver, No. 6564, on the left side ; on the 

 riffht side the American skull shows a faint indication of the 



