lOG PEOCEEDINGS OF UNITED. STATES NATIOXAL MUSEUM. 



somewhat pointed, the length of the anterior margin 1| times interor- 

 bital width, and nearly 14 times the free margin 5 length of pectoral 

 about one-sixth the total length of the tish. 



Color light slaty-gray ; belly white ; middle line of back posteriorly 

 and upper edge of tail blackish; tips of all the fins distinctly blackish, 

 es])ecially the pectorals and lower lobe of caudal, 



This species is rather common at Mazatlan, where several young 

 specimens were taken, the largest (29549), a young male, being 30 inches 

 in length. A species thought to be the same was also seen at Panama, 

 but no specimens were brought to the museum. 



Carcharias longurio, sp. uov. (28306, 28330, 28331, 29541, 29551.) 



fSqiialHs {Scolioclon) porosxs Poey, Memorias Cuba, II, 339 tab. 19, f. 11, 12, 



1861 (Cuba.) (Not Carcharias 2>orosus Rauzaui, 1839.) 

 '? Scoliodo)! jwrosHfi Poey, Syuops. Pise. Cubeus, 1868, 452. (Cuba.) 



Subgenus Scoliodon Miiller and Heule. 



Body rather slender and elongate, the back little elevated. Head 

 depressed, long and narrow, rather pointed anteriorly. Length of snout 

 from mouth greater by about the diameter of the eye than the distance 

 between the angles of the mouth and a little more than half greater 

 than the distance from a line connecting the angles of the mouth to the 

 tip of the chin. 



Eye rather large, a little nearer nostril than angle of mouth ; distance 

 from eye to nostril scarcely half the distance from nostril to tip of 

 snout. 



Interorbital width two-fifths distance from snout to first gill-o])ening, 

 somewhat less than length of snout measured from eye. 



Angle of mouth with a i)it from which a furrow extends on the lower 

 lip a distance about etjual to the length of a nostril, and on the upper 

 lip considerably farther. Length of nostril about two-thirds diameter of 

 eye, and about half its distance from eye, the anterior margin with a 

 narrow projecting flap. Distance between outer angles of nostrils 

 slightly more than their distance from tip of snout. 



Teeth of the upper jaw subtriangular, very oblique, deeply notched 

 on the outer margin, those of the lower jaw similar, narrower and rather 

 less oblique. Bases of upper teeth with a few weak serrations. Ifo 

 evident serrations on enameled parts of any of the teeth. Number of 

 teeth about ff. Teeth all somewhat narrower and less oblique than in 

 Carcharias {ScoUodon) terra'- nova'. 



Gill openings narrow, the last two over base of pectoral, the depth of 

 one about f the distance from snout to mouth, the middle or largest about 

 half the length of the branchial area; first and last gill-openings about 

 equal. 



Top of head with numerous mucous pores. A series of numerous 

 large pores in a line above angle of mouth, and a baud of them behind 

 eye, extending upward on the nape. Under side of snout with many 



