NO. 5 TELESCOPING OF THE CETACEAN SKULL 45 



the structure of the orbit and of the maxillary above and behind the 

 orbit differs in no essential feature, so far as can be judged from the 

 plate representing the lateral aspect of the skull, from the conditions 

 present in Globiccphala; on the other hand the positions of the 

 foramina near the orbit as figured from in front suggest those in the 

 type specimen of Cope's " Paracctus " nicdiatlmiticus. The names 

 Eudelphis and Homwocctns were based on vertebrae resembling the 

 peculiar atlas of the sperm whale. It is therefore not impossible that 

 they refer to members of the family Physeteridce. Various names of 

 supposed physeteroids, such as Bakcnodon, Eitcetus, Hoplocctiis, Pa- 

 Iccocefus, Physctodon, have been applied to isolated teeth. Some of 

 these teeth as described and figured are of the same tusk-like type as 

 those of the sperm whale. Others resemble the enlarged teeth of such 

 delphinids as Orcinus and Pscudorca, in which the growth is not tusk- 

 like, the portion below the well-defined, enamel-covered crown being 

 merely enlarged and thickened, but with a closed base. The system- 

 atic position of the animals which bore these teeth is conjectural. 

 Though nothing of the kind is yet known it does not seem impossible 

 that a physeteroid might have teeth of the Orcinus type ; while the in- 

 conclusiveness of the evidence furnished by isolated tusk-like teeth is 

 shown by the fact that this kind of tooth growth occurs not only in the 

 sperm whale and Kogia, but also in the beaked whales, the narwhal 

 and the white whale. Although in appearance extremely specialized, 

 chiefly on account of the unusual basining of the facial region, the 

 skull of Physeter is, like that of Kogia, more primitive in its ground 

 plan, as shown by the structure of the narial passage, the palatine and 

 the pterygoid, than that of any other known toothed cetaceans except 

 the agorophiids. 



Kogiidcc. — While the living genus Kogia agrees with Physeter in 

 general structure it differs so much in details that it probably repre- 

 sents a special family. The discovery of fossil forms may, however, 

 eventually result in obscuring the apparent distinctness of the two 

 groups. The more important of the details which, taken together, 

 now seem of family value are : the fusion of all the cervical vertebrae 

 into a single mass distinct from the first dorsal as in the ziphiids and 

 the typical dolphins ; the situation of the orbit at a level mostly behind 

 that of the narial passage ; the presence on the forehead ofa distorted 

 but evident longitudinal median ridge extending backward from the 

 narial orifice; the fusion of the jugal and lacrimal into a mass lying 

 entirely anterior to the orbit and having a superficial exposure nearly 

 equal to that of the frontal. No fossil representative of the family 



