Fishes of the Western North Atlantic 405 



rus); (f) the outer corners of its pelvics are only about at a right angle (about 115° in 

 obscurus) ; (g) its dermal denticles have a larger number of marginal teeth and ridges in 

 specimens of equal size; and (h) its upper teeth are more strongly oblique, more deeply 

 incised outwardly and more coarsely serrate basally than those of obscurus. 



Among carcharhinids of the west coast of America, springeri resembles most nearly 

 platyrhynchus (Gilbert), 1 89 1, in its teeth and fins. But the length of its snout in front of 

 the mouth is considerably less than the breadth of the mouth (a little longer than breadth of 

 mouth in platyrhynchus), and its fins show no trace of the white edgings that are so con- 

 spicuous in platyrhynchus. In combination these differences seem sufficient to demand rec- 

 ognition in nomenclature, especially in view of the geographic discontinuity between the 

 areas of occurrence of the two sharks. 



Springeri is similar to galapagoensis Snodgrass and Heller, 1905, in the teeth and 

 snout, but separated from it by the shapes of the first dorsal and pectoral fins, much larger 

 eye relative to the lengths of the gill openings, and by the fact that its second dorsal is only 

 very little smaller than its anal in area. 



Description. Proportional dimensions in per cent of total length. Female, 805 mm., 

 from Cozumel, Mexico (U.S. Nat. Mus., type, No. 37140- 



Trunk at origin of pectoral: breadth 12.O; height 1 1.4. 



Snout length in front of: outer nostrils 3.1 ; mouth 6.6. 



Eye: horizontal diameter 2.1. 



Mouth: breadth 8.9; height 5.7. 



Nostrils: distance between inner ends 6.$- 



Labial furrow length: upper 0.6. 



Gill opening lengths: ist 2.3; 2nd 2.6; 3rd 2.7; 4th 2.6; 5th 2.2. 



First dorsal fin: vertical height 10.7; length of base 9.9. 



Second dorsal fin: vertical height 3.3; length of base 4.5. 



Anal fin: vertical height 3.9; length of base 4.9. 



Caudal fin: upper mzrgm 29.85 lower anterior margin 14.2. 



Pectoral fin: outer margin 19.9; inner margin 5.2; distal margin 15.6. 



Distance from snout to: ist dorsal 30.73 2nd dorsal 58.8; upper caudal 70.2; pec- 

 toral 20.5; pelvics 47.9; anal 58.8. 



Interspace between: ist and 2nd dorsals 20.7; 2nd dorsal and caudal 7.7; anal and 



caudal 6. i . 



Distance from origin to origin of: pectoral and pelvics 27.2; pelvics and anal i i.o. 



General form moderately stout. Trunk height at origin of ist dorsal (where highest) 

 about Vs of length to origin of caudal. Body sector to cloaca somewhat longer than tail 

 sector. Midline of back with a low but unmistakable dermal ridge between dorsals. In the 

 preserved state there is also a similar ridge between 2nd dorsal and caudal, but since this 

 lies along the bottom of a groove of muscular contraction we question whether it is a normal 

 feature. Upper precaudal pit strongly marked, subangular in outline, the lower pit lunate, 

 less distinct than upper. Dermal denticles closely and regularly overlapping, broader 



