722 PLAGIOSTOMATA— SELACHOIDEI. 



Family, II— LAMNID^. 



Spiracles, if present, minute. No membrana nictitans. Mouth inferior and crescentic. Nostrils not 

 communicating with the mouth. First dorsal spineless, and placed opposite the interspace between the 

 pectoral and ventral fins : an anal fin present. 



I have (p. 713) described a shark, Carcharias tricuspidatus, the teeth of which so closely resemble those 

 seen in Odontaspis, that specimens have been erroneously referred not only to that Genus but to the 

 0. Americanus. The absence or presence of the pit at the root of the caudal fin is one character which at once 

 distinguishes the two forms, for if they were identical species the character of the pit at the base of the caudal 

 fin as a distinguishing guide would have to be given up, not only as a generic but even as a specific character. 



Genus 1 — Lamna, Cuvier. 



Oxyrhina, Agassiz. 



Spiracles, -if present, minute. No membrana nictitans. Mouth wide. Gill-openings large. Teeth large, 

 awl-shaped, smooth or sometimes with a small lateral basal cusp on either side. The first dorsal fin spineless, placed 

 opposite the interspace between the bases of the pectoral and ventral fi,ns. Lower caudal lobe large. A keel aloiig 

 the side of the tail. A pit at the base of the caudal fin. 



1. Lamna Spallanzanli, Plate CLXXXVI, fig. 2. 



Lamna punctata, Storer, Bost. Journ. Nat. Hist, ii, 1839, p. 534, pi. viii, f. 2, and Mem. Amer. Acad, ix, 

 1867, p. 225, pi. xxxvii, fig. 1 ; Dekay, New York, Fauna, Fish. p. 352, pi. Ixiii, f. 206 (not Mitchell) ; 

 Poey, An. Soc. Esp. v, p. 381, t. xiv, fig. 1. 



Oi-yrhina Spallanzanii, Bonap. Faun. Ital. Peso. t. cxxxvi, f. 1 ; Dumeril, Hist. Nat. Poiss. i, p. 408. 



Oxyrhina gomphodon, Miiller and Henle, Plagiost. p. 68, t. xxviii. 



Istirojisis Dekayi, Gill, Ann. Lye. Nat. Hist. New Tork, vii, p. 409. 



0.ryrhina ptinctata, Dumeril, 1. c. p. 409. 



Lamna spallanzanii, Giinther, Catal. viii, p. 390; Klunz. Fische Roth. Meer. 1871, p. 669. 



Snout pointed, angle of the mouth about midway between the nostril and the first gill-opening. 

 Gill-openings very wide. Teeth — -L| on either side, awl-shaped, with sharp but entire lateral edges, and 

 destitute of basal cusps : the third on either side of the symphysis of the upper jaw smaller than those on 

 either side of it. Fins — the base of the first dorsal rather nearer the pectoral than the ventral fin. Pectoral 

 falcifonn, its inner being one-fourth of the length of its outer margin. Second dorsal and anal small, situated 

 opposite one another. The keel on the side of the tail commences anterior to the base of the second dorsal 

 and anal fins. Colours — gray, becoming lighter beneath. 



Habitat. — Eed Sea and Indian Ocean, also the Atlantic and Mediten-anean. The figure is from one of 

 Sir W. Elliot's di-awings, which was taken from an example captured at Madras. It attains to a very 

 large size. 



