117 



special pleading, " which, together with the great improbability of the 

 same species being found in such widely different regions," may justify 

 its separation from the M. Sowerbiensis. If so, I would suggest that 

 the specific name of Thomsoni, Krefft, be retained, in regard to the 

 memory of one whose loss I consider as a public calamity to this 

 country. 



Mesoplodon Layaedii, G-ray. Layard's Ziphius. 

 Synonyms — ZipMus Layardii, Gray, S. & W., p. 353. 



Dolichodon Layardii, Gray, Suppl. p. 101. 

 Inhab. Cape of Good Hope. 



Teeth tj, " in the middle of the sides of the lower jaw. Teeth of the 

 male very long, Strap-shaped, produced, arched obliquely, truncated at 

 the end, with a conical process on the front of the terminal edge. 

 Lower jaw weak, very slender in front. Symphysis elongate." Gray. 



This singular cetacean is only known from the solitary specimen of 

 a skull in the British Museum ; and the striking peculiarity which it at 

 once presents to observation consists in the elongated teeth of the 

 mandible, for these " arch over the outer surface of the upper jaw, and 

 thus prevent the animal from opening its mouth beyond a very limited 

 extent." 



It has been suggested that this strange dental growth, certainly 

 unique, if natural, in the history of living beings, and threatening to 

 prove ultimately fatal to the very existence of its possessor, might have 

 been the result of individual peculiarity, or malformation ; but Dr. 

 Gray thinks otherwise, and has recently formed the genus Dolichodon, 

 or long-toothed, for its reception. It is very desirable that several other 

 examples in a similar state of dental perfection should be brought to 

 light, for otherwise there is nothing to excite surprise. 



Oenus DioPLODON,' Gervais. 



Skull high, narrow, nearly flat behind ; brain-cavity very small ; beak 

 depressed, much elongated, tapering to a point ; much narrower and 

 shorter than, and received within the teeth of, the mandible ; lower 

 jaw broad behind, contracted in front ; rami high on the sides, rather 

 stout, terminating upwardly in front of the teeth in an arched manner ; 

 symphysis short, about one-fifth of the entire length of the ramus ; 

 teeth large, compressed, greatly elevated, being embedded in large 

 sockets, which swell in a rugged manner from the upper surface of the 

 rami, giving the mandible a peculiarly distinctive form. 



' f Is, twice, '6ir\a, arms, and oSotJr, tooth, that is, armed with two teeth. 



