ISURUS OXYRHYNCHUS. 37 



Head to the fifth gill opening nearly one fourth of the total length; body 

 moderately robust; snout subconical, elongate, sharp. Teeth smaller than 

 those of /. oxyrhynchus, similarly without basal denticles, with a sharp slender 

 curved cusp, and with the third tooth at each side of the middle of the mouth on 

 the upper jaws much smaller than the second or the fourth. Pectorals sub- 

 falciform, outer portion rather narrow, front margin about twice as long as the 

 base and the inner margin together, inner angle rounded. First dorsal a short 

 distance behind the pectorals, front margin straighter and upper angle sharper 

 than in /. glaucus. Second dorsal little in advance of the anal and nearly its 

 equal in size. Ventrals about midway from the bases of the pectorals to the 

 caudal, nearer to the dorsal than to the anal. Extremities of the caudal sharp, 

 front margin of the subcaudal lobe about two thirds of the length of that of the 

 supracaudal. Attains a length of more than ten feet. 



Bluish to ashy brown; white on the lower surfaces, color sharply defined 

 on the level of the caudal keels. 



This species is distinguished from /. punctatus by a sharper snout, narrower 

 and longer pectorals, narrower dorsal and caudal, and by the positions of the 

 dorsals. A higher more erect and sharper dorsal, placed farther back, and 

 narrower and more pointed pectorals separate it from /. glaucus. The backward 

 insertion of the dorsal, and smaller teeth, and the forward position of the second 

 dorsal as compared with the anal prevent confusion with /. oxyrhynchus. Non- 

 acquisition of denticles on the teeth of adults and the rearward insertion of the 

 first dorsal limit its affinities with /. nasus. 



Gulf of Mexico to New York; West Indies. 



ISURUS OXYRHYNCHUS. 



Cane di mare di Messina Spallanzani, 1793, Viagg. alle due Sicil., 4, p. 325. 



Isurus oxyrinchus Rafinesque, 1810, Carratteri, p. 12, pi. 13, f. 1; Jordan & Gilbert, 1883, Hull. 16, 



U. S. nat. mus., p. 29; Jord. & Everm., 1896, Bull. 47, U. S. nat. mus., p. 48. 

 I surics spallanzani Rafinesque, 1810, Ind. itt. Sic, p. 45, 60; Jordan & Gilbert, 1883, Bull. 16, U. >\ 



nat. mus., p. 874. 

 Lamna oxijrhina Owen, 1840, Odont., p. 28, pi. 3, f. 1, pi. 5, f. 1. 

 Oxyrhina gomphodon, Muller & Henle,1841, Plagios., p. 68, pi. 28; Bocage & Capello, 1866, Plagios., 



p. 13. 

 Oxyrhina spallanzanii Bonaparte, 1841, Icon. Fauna Ital., Pesci, pi. 53; .A.gass., 1843, Rcch. poiss. foss., 



3, p. 276, pi. G, f. 2; Dumeril, 1865, Elasm., p. 408; Doderlein, 1881, Man. ittiol. ]\Iedit., 2, p. 62, 



Kynon. part; Moreau, 1881, Poiss. France, 1, p. 298. 

 Lamna spallanzanii Gunth., 1870, Cat. fishes Brit, mus., 8, p. 390 (excl. synon). 



Outlines similar to those of /. nasus or /. punctatus; body apparently a 

 trifle more slender than in either. Snout long, pointed, subconical, slightly 

 angular in a cross section. Crown depressed in a low arch transversely. Nos- 



