.296 Roland Trbnen, F.B.S. — Note o?i [Aug. 29, 



distance behind the apex of the mandible, are greatly compressed 

 laterally (so as to resemble a thick strap), and slant considerably 

 backward, while they are sufficiently long and curved inward 

 superiorly as to meet, or almost to meet, above the long and narrow 

 snout or beak. At the tip of each of these singular tusks there is 

 in front a conical compressed projection, looking like a small tooth 

 artificially inserted ; this Prof. Moseley {Notes hy a Naturalist on the 

 " Challenger^'' 1879, p. 158) regards as the original small cap of 

 dentine of the tooth of the young animal, which, without increasing 

 in size, is carried up by the apparently abnormal growth of the fang, 

 vthe latter constituting the bulk of the tusk. 



Both Mr. Layard and myself were at once struck with the obvious 

 difficulty that, if this singular position and form of the tusks were 

 not due to an individual aberration or monstrous growth, the case 

 was one of a great mammal with its jaws naturally so locked together 

 as to be unable to open its mouth for more than a very little distance. 

 Both Dr. Gray and Professor Owen were inclined to look upon the 

 •single original specimen as shewing merely an individual malfor- 

 mation ; but, as Prof. Flower has recorded, Mr. Layard possessed 

 a single tooth of another individual having an exactly similar 

 conformation, and the discovery by Prof. Moseley (while here in 

 1873 on the Cruise of the " Challenger") of the lower jaw, with quite 

 similar tusks, of a third example rendered it almost indisputable that 

 the case was one of normal occurrence in this species. It is not 

 known whether, as Prof. Flower suggests, the tusks are peculiar 

 to the male animal. In connection with the difficulty referred to, 

 it occurred to me in 1865, when examining the type specimen, that 

 possibly the flattened tusks (which even in situ on the skull showed 

 some elasticity in yielding and separating when the lower jaw was 

 pressed downward) were to some extent movable at the will of the 

 animal ; and I have found, in the account by the late Sir Julius 

 Haast of the capture of an allied Ziphioid Whale {Berardtus Ar7iousi) 

 near Canterbury in New Zealand, that an eye-witness of the dying 

 struggles of this stranded specimen observed its front teeth to be 

 movable and protrusible. The food of these Cetaceans, as far as 

 ascertained, consists, both in the Northern and Southern hemispheres, 

 of Octopus and allied cuttle-fish ; and, if the mouth of Mesoplodon 

 Layardii is as closely locked by the over-arching tusks as it appears 

 to be, it is difficult to understand how it can capture these active and 

 watchful cephalopods. 



