PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 103 



mouth. Nostril a little nearer eye tlian tip of snout. Interorbital width a 

 trifle more than half distance from snout to base of pectoral, about twice 

 length of snout, measured from eye. Angle of mouth with a deep pit 

 which scarcely extends as a furrow on either lip. Islostrils near margin 

 of head, their length half their distance from eye, and about the same 

 as length of eye, the anterior margin with a moderate flap. Teeth ot 

 both jaws narrowly triangular, more than twice as high as broad, those 

 of the upper jaw rather broadest, all of them nearly erect and not evi- 

 dently notched on the outer margin. Edges of teeth appearing minutely 

 serrulate under a lens. Teeth about |{f. 



Gill-openings rather deep, the last two over the base of the pectorals, 

 the depth of them about equal to the distance from nostril to middle of 

 eye, the branchial area scarcely longer than broad. 



Free margins of all the tins concave. Insertion of tirst dorsal rather 

 nearer pectorals than ventrals, its distance behind pectoral being nearly 

 equal to the length of its anterior margin. Anterior lobe, when de- 

 pressed, reaching past the base of the tin, but not to the end of the pos- 

 terior lobe, which reaches nearly to the base of the ventrals. Length of 

 base 01 first dorsal slightly more than its (vertical) height, and notably 

 less than interorbital width. Distarice between dorsals slightly more 

 than twice the base of first dorsal, a little more than three times base of 

 second. 



Second dorsal similar in form to the first dorsal, its base one-fifth 

 shorter, its posterior lobe reaching to within an eye's diameter of the 

 pit at root of caudal. 



Lower lobe of caudal half length of upper, both of the ordinary form 

 in this genus ; length of the upper lobe a little less than the distance 

 from snout to posterior part of root of pectorals, a little less than one- 

 fourth the total length. 



Anal smaller than second dorsal and proportionately higher, its mar- 

 gin deeply concave, its anterior lobe reaching the tip of posterior when 

 reflexed ; length of anterior margin about equal to base of second dor- 

 sal." Distance of anal from caudal a little more than its base, and a 

 little less than distance of front of anal from base of ventials. Middle 

 of anal under middle of second dorsal. 



Ventrals moderate, their anterior margins about equal to the distance 

 between the angles of the mouth. 



Pectorals rather large, their angles not acute; their tips reaching a 

 little past front of dorsal; tlieir anterior margins half longer than inter- 

 orbital width, and 2^ tiines the free margin. 



Color uniform slaty-gray; all the fins edged with darker brownish, 

 darkest on the lower lobe of the caudal, but nowhere fully black. 



b. Description of a large specimen : 



A large example of this species, some 10 feet in length, was speared 

 from the wharf at Mazatlan. The jaws of this specimen (collector's 

 number, 907) were taken. 



