102 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



slender, the head must have resembled that of such long-beaked forms 

 as Platanista, but if the maxillae were expanded, which is improbable, 

 the head itself may have been broad and obtuse, as in Kogia or Physeter, 

 and the lower jaw small and underhung. In either case, the appearance 

 of the animal would be very different from that of any of the existing 

 ziphioids, in which the snout is comparatively short and thick, or, in 

 other words, of the shape commonly called " bottlenosed." 



In Anoplonassa, the vessels and nerves which supply the mandible 

 instead of issuing anteriorly through a number of foramina scattered 

 irregularly along the rami in the vicinity of the symphysis, as is usual 

 in some ziphioids and most Delphinidae, emerge close to the tip of the 

 jaw in a nearly symmetrical fashion, there being two large foramina on 

 each side immediately below the alveolus of the terminal tooth, with a 

 smaller one between them. The foramina of each side are joined poste- 

 riorly by a quite deep groove, which runs along the inferior surface of 

 the jaw nearly to the end of the fragment. The symphysis is strongly 

 carinate in the median line, the internal edge of each half of the jaw 

 being raised into a prominent ridge, which forms the inner boundary of 

 the groove already mentioned. The keel extends from the tip of the 

 mandible nearly to the end of the fragment, but fades out gradually 

 posteriorly. 



A very similar arrangement of foramina and ridges occurs in Ziphius 

 and in Berardius. In the former genus the ridges forming the keel are 

 shorter, and somewhat divergent. The canals extending backward from 

 the anterior terminal foramina are much less strongly developed than in 

 Anoplonassa and run into a large and sharply defined mental foramen, 

 situated in line with the posterior end of the symphysis. The anterior 

 foramina instead of remaining separate, are usually merged together, 

 forming an opening of considerable size. 



The conformation of Berardius is similar to that of Ziphius, except 

 that usually the mental foramen assumes the form of a long trough 

 situated a little in front of the posterior end of the symphysis and 

 followed posteriorly by one or more additional foramina. It is probable 

 that at the posterior end of the symphysis of Anoplonassa there was a 

 similar foramen or trough. That it is not found on the type specimen 

 is an additional indication that the posterior end of the symphysis is 

 lacking. 



While the form of the alveoli, alveolar groove, and mandibular fora- 

 mina of Anoplonassa denote clearly that it belongs to the subfamily 

 Ziphiinae, it obviously represents a section of that subfamily distinct 



