268 



PROF. HUXLEY ON THE CRANIAL AND 



[Apr. 6, 



inagellanicus ; but, so far as the measurements of his figures of the 

 teeth permit me to form a judgment, C. griseus differs in no respect 

 from some specimens of C. cancrivorus. With a shorter skull, Bur- 

 meister's specimen of C. magellanicus has larger sectorial teeth than 

 either of the specimens I have seen. 



In the lower jaws of two specimens of C. cancrivorus, and in one 

 of C. magellanicus, in the British Museum, there is a well-formed 

 though small fourth molar ; and in a third specimen of C. cancri- 

 vorus there is a curious abnormal structure, consisting of a bunch 

 of five minute crowns of teeth (whether united by their roots or not 

 cannot be made out without injuring the specimen) in the place of 

 the fourth lower molar on the right side. 



Fig. 15. 



Side view of the skull oi Icticyon venaticus: | uat. size. 



Van der Hoeven ' has described and figured a skull with a third 

 upper molar on both sides, which he ascribes to C. asarcc, but which, 

 according to Burmeister, belongs to O. cancrivorus. 



In C. cancrivorus, therefore, the persistence of ^-j seems to be a 

 common occurrence, while ^^ is found occasionally. Thus it would 



appear that we have under our eyes, in this species, another stage in 

 the modification of the primitive dentition of the (^anidte, which, as 



' " Over het gescblacht Icttcyon van Lund," Verhandelingen der Eoninklijke 

 Akademie van Wetenschappen, Am&terdam, iii. 1856. 



