400 PROCEEDINGS OF THE ACADEMY OP 



tion " macrodus" as a substitute for (l Americanus ; " but the former quoted 

 description is sufficient to determine positively the intended species, and hav- 

 ing three years priority, the specific name must be retained. 



The article in the American Monthly Magazine we have not been able to ex- 

 amine. 



In the Museum of the Academy, there is preserved a specimen, mounted, 

 and somewhat distorted; and a set of jaws, belonging to the same species, 

 which, if it were not for the descriptions of Mitchill, would be considered non- 

 descript ; as the specimens present certain characteristics of dentition not ex- 

 hibited by any heretofore well defined species of our coast, although in perfect 

 correspondence with the dentition of Odontaspis taunts, 0. ferox, and Lamnia 

 cornubica ; but as none of the above mentioned three sharks are known to be 

 inhabitants of our coast, and as Eugomphodus griseus, to which the description 

 of Mitchill might be possibly referred, differs in the dentition from Odontaspis 

 Americanus, by the dentulures being vaguely defined prominences instead of 

 sharply denned basal teeth, which is emphatically dwelt upon by Mitchill, it 

 is evident that the Squalus Americanus, Mitchill, is the species that is described 

 in detail in this paper, and which, belonging to the genus Odontaspis, Agassiz, 

 will hereafter be so referred. 



In the " Recherches sur les Poissons fossiles," tome 3d, p. 287, Professor 

 Agassiz established a sub-genus from Lamna, Cuv., under the title Odontaspis, 

 for the reception of two species, Odontaspis taurus and 0. ferox. This sub- 

 genus he characterized as follows : 



Les dents de Lamna sont plates et se rapprochent par leur forme des dents 

 d' Otodus ; dont elles different cependant par leur moindre largeur et par leurs 

 cones latereux beaucoup plus petites. Les dents d' Odontaspis, au contraire, 

 sont plus cylindriques, plus tordues, et out des cones latereux plus long et 

 plus pointus. 



Miiller and Henle* have raised the sub-genus, framed by Agassiz, to the rank 

 of a genus, giving as its characters, 



Ouvertures branchiales grandes, toutes situees en avant des pectorales. 

 Eventes tres petites. Second dorsale et anale grandes. Lobe superior de la 

 caudale allonge comme dans les carcharias. Fossette caudale indistinct ou 

 manquent completement. Les carenes de la queue des Lamnies manquent.f 



The specimen in the Academy's Museum, to which we consider the descrip- 

 tions of Mitchill applicable and belonging, is included in the scope of the above 

 generic diagnoses ; and the affinities of the specimen are as inclusively com- 

 prehended in the enumerations of the characters of Odontaspis, in this, the 

 third species of the genus, as its specific variances are distinctly exhibited, 

 from either 0. taurus or 0. ferox. 



Odontaspis Americanus, Abb. 



Squalus Americanus, Mitch. Rep. in part of Fishes of New York, p. 27. 

 Squalus Americanus, Mitch. Trans. Phil, and Lit. Soc. of N. Y. p. 488. 

 Squalus macrodus, Mitch. Amer. Month. Mag. vol. 2, p. 328. 

 Squalus Americanus, De Kay, Fishes of New York, p. 366. 

 Squalus Americanus, Storer, Synop. Fishes of North America, p. 

 Squalus Americanus, Gill. Cat. Fishes of East Coast of N. Amer. in Proc. Acad. 

 N. S., Philad. 1861, p. 60. 

 Head broader and blunter than in Odontaspis taurus. The extremity of the 

 snout approximates to three times as far in advance of the anterior margin of 

 the orbit, as the posterior margin of the orbit is anterior to the angle of the 

 mouth. The nostrils are situated well forward and near the extremity of the 



System. Besch. der Plagiostomen. 



t Recher. sur les Pois. foss., tome 3, p 287. Foot note. 



[D 



ec. 



