1S82.] SIMCCIKS OK HYl'EROODOV. 395 



the " infraorbital " foramina are smaller — a character probably related 

 to the smaller surface-region to be supplied by the nerves and vessels 

 which pass through it, occasioned by the reduced size of the crests and 

 a possibly shorter rostrum, — and that the temporal fossa is shorter 

 from before backwards, and higher vertically, more resembling that 

 of Ziphius cuvirostris. 



There is little, in sucli portions of the under surface of the skull 

 as are preserved, that shows any striking difference from the common 

 species. 



A sufficient portion of the vomer is preserved to show that it was 

 not complicated by the adherence to it of an ossified medio-rostral 

 bone, in which respect it agrees with all known specimens of Hy- 

 peroodon and Berardius, and differs from the adults of Ziphius and 

 Mesoplodon. 



Owing to the destruction of some of the more prominent of the 

 external parts of the cranium, very few dimensions can be given 

 beyond those at p. 393 ; but the following comparisons may be 

 useful : — 



H. ji^cnifrons. H. rostratus. 

 millim. millim. 



Width between anteorbital notches 432 385 



Width of base of eacii maxillaiy crest oppo- 

 site anteorbital notches 160 127 



Interval between crests 105 130 



As the cranium thus differs from that of H. rostratus in the com- 

 parative lowness and rounded form of the maxillary crests, from II. la- 

 tifrons (with its enormous, vertically raised, flat-to|)ped and con- 

 verging crests) it deviates in a so much more marked degree that a 

 detailed comparison between them is quite unnecessary '. 



AVith so imperfect a knowledge even of the cranium, and with 

 absolutely none of the remainder of the animal's organization, any 

 determination of its generic affniilies can only be provisional ; but if 

 the genus Hyperoodon include both H. rostratus and H.latifrons, 

 there is no reason against this new form being contained in it also. 

 If, on the other hand, they are separated, as was done by the late 

 Dr. Gray, it would have to form a distinct genus, as it differs quite 

 as nmch, or more, from H. rostratus in one direction as H, lati/rons 

 {Lagenocetus latifrons of Gray) does in the other. Not wishing 

 to multij)ly genera, I prefer the former course, and shall consider it 

 a Hyperoodon ; and as it differs from both of the other species in the 

 comparative flatness of the fore part of the head (which looks ex- 

 ternally like, although not strictly homologous with, the animal's 

 forehead), it may be specifically called planifrons. It is evidently 



' H. hi/ifrons is coiisiclercd by some zoologists to be the adult male of H. ros- 

 tratus. Oiiptain David Gray, of Peterhead, who is perfectly familiar with both 

 forms, has furnished me with some evidence strongly tending to the opposite 

 conclusion. .1 hope, with further information from the same source to be col- 

 lected during the present whaling-season, to be .soon in a position to clear up 

 this important and still doubtful question in cetologj-. 



