424 ZOOLOGY. 



spectator be placed at quite a considerable distance, many mistakes might 

 readily have been introduced into drawings, which are, with a few excep- 

 tions, the only data in our possession. Thus, the small s^^ermaceti (P. cato- 

 don), the blunt-headed cachalot (P. trumjoo), the round spermaceti whale 

 (P. cylindricus), the small-eyed cachalot (P. microps), the great-finned 

 cachalot (P. midar), and the bunched cachalot (P. gibbosns\ are still doubt- 

 ful species ; the two-toothed cachalot of Sowerby (P. hidens sowerhyi) belongs 

 to the family of Heterodonts, but is not sufficiently known to decide upon 

 its real place. It constitutes a genus by itself, nearly allied to Delphinus 

 proper, with a peculiar organic structure, uniting Physeteridte to Delphinidse 

 more intimately than any other group. 



The fishing grounds for the spermaceti whale are from the Seychelles 

 Isles to Timor, and all the coast of New Holland as far as Shark's Bay, the 

 Japanese seas as far as the Philippine Isles, and to the eastward as far as 

 California. 



The fossil remains of Physeter, which have already been discovered, 

 have not been made the subject of a careful examination. Fragments were 

 obtained in France and England, and, we are told, also in North America ; 

 but the specimens alluded to here, and upon which the genus Nej^hrosteon 

 has been established, are said to belong to a recent and still living species. 



The generic name Arionius has, however, been given to a skull disco- 

 vered in the meiocene of German}^ The upper part of its posterior surface 

 is concave, and along the middle a vertical ridge is seen, vanishing as it 

 goes downAvards ; the forehead is flat, horizontal, and remarkably broad, 

 decreasing gradually in the elongated snout ; the sides, formed by the tem- 

 porals and frontals, are very concave from above downwards ; the nasal 

 canal widens in its way along th% snout; the jaws are armed with numerous 

 teeth ; those on the lower jaw are longer and more acute, with almost 

 rounded roots, and the crown pointed, conical, scarcely bent, provided in 

 front and behind with a sharp edge, whilst on the sides a slight, not quite 

 regular furrow is to be seen. A single species {A. servatus) is described. 



This genus may perhaps prove hereafter to belong to the next family, or 

 even an intermediate between both the latter and this. 



The genus Balce7iodon- is known by a single fragment of a tooth, whose 

 structure differs from the same parts in Physeter in having the dentine layer 

 thicker. The species is designated under the name of B. physaloides. 



Fam. 3. Delphinidse, constitutes a very natural group among Cetacea. 

 It is composed of the smallest species of the order, although some of them 

 attain a considerable size, as between twenty-five and thirtj^-six feet in 

 length. The dolphins have a fusiform bod}^, which seems completeljl 

 deprived of a neck, the anterior region of which terminates by a snout 

 more or less elongated, whilst the posterior region, the tail, is terminated 

 by the horizontal fin common to all Cetacea. The size of the head is not 

 disproportionate when compared to the body. The jaws are nearly of 

 equal length, and both are furnished with a row of more or less conical or 

 compressed teeth, varjdng in number in the particular species. They are 

 developed on the margin of the maxillaries, and in some species inserted in 

 628 



