PHYSETEKID^. 67 



Choneziphius planus (Owen^). 



Syii. Ziiihius planus, Owen 2. 



This species, which is equal in size to the preceding, is referred 

 to the present genus by Gervais in the ' Osteographie des Cetaces,' 

 p. 418. The type specimen is not sufficiently perfect to admit of 

 determining whether the form described by Lankester ^ under the 

 name of C. paclcardi may not be specifically the same. 



Hah. England. 



384:98. The cranial rostrum ; from the Eed Crag of Suffolk. This 



{Fig.) is the type specimen, and is described and figured by 



Owen, op. cit. p. 16, pi. xi. fig. 1, under the name of 



Zipliius planus. It is also figured by Gervais in the 



^ Oste'ographie des Cetaces,' pi. xxvii. fig. 16. No history. 



Genus MESOPLODON, Gervais \ 



SyD. Dionlodon, Gervais *. 



BelemnoziphiuSj Huxley ^. 



The mandible has a single pair of laterally-compressed pointed 

 teeth, generally situated at some distance behind the apex. The 

 narial region of the cranium resembles that of Ryperoodon^ but the 

 nasals are narrower and more deeply sunk between the premaxillae. 

 There are no maxillary tuberosities, and the rostrum is very long 

 and narrow ; in the latter the premaxillae are in contact with 

 the adjacent bones, and soldered throughout the whole length of 

 their inner surfaces; in old specimens the mesethmoid cartilage 

 completely ossifies and forms a well-defined band on the superior 

 surface of the rostrum, which is solid throughout, and only shows 

 a small portion of the vomer on its inferior aspect. The posterior 

 portion of the periotic is produced and pointed, the articular ridge 

 on. the tympanic aspect of the same rather low, the accessory 

 ossicle small and oval, and the anterior articular facette for the 

 tympanic dee^jly concave. Two or three of the cervical vertebra 

 are united. 



1 Crag Cetacea (Mon. Pal. Soc), p. 16 {\^1^).—Ziphius. 



^ Loc. cit. 



^ Quart. Joiirn. Geol. Soc. vol. xxvi. p. 502 (1870). This name is of later 

 date than C. plaims. 



* Ann. Sci. Nat., Zool. ser. 3, vol. xiv. p. 16 (IS.'^O). For a full synonymj see 

 Flower, ' Trans. Zool. Soc' vol. viii. p. 208. 



5 Zool. et Pal. Franc^aisea, 1st ed. vol. ii. Exp. No. 40, p. 4 (1848-52). 



^ Quart. Journ. Geol. Soc. vol. xx. p. 888 (1864). The term was appUed to 

 all the Crag forms included by Ovyen in ZijJiius. 



p2 



