REVISION OF CARCHARHINID SHARK GENERA — SPRINGER 603 



posterior edge of lower lobe; first dorsal dark, sometimes with a 

 darker posterior edging; second dorsal uniformly dark or black in 

 adults, usually with an irregular blackening of the apex in young. 



A low interdorsal ridge present in all well-preserved specimens 

 examined. Both precaudal pits present, the upper better developed. 



Growth changes: There is a general tendency for distance from 

 snout tip to outer nostrils, eye, mouth, and first gill-opening to de- 

 crease in percent of t.l. with increased t.l. Distance between inner 

 corners of nostrils, eye diameter, length of upper caudal lobe, and 

 notch depth also decrease in similar manner. Distance from snout 

 tip to second dorsal origin and length of anterior and distal margins 

 of pectoral fin tend to increase in percent of t.l, with increased t.l. 



In large specimens there is a tendency for the axis of the upper 

 caudal lobe to become raised in relation to the horizontal axis of 

 the body, 



InsuflBcient information is available to estabhsh the size at which 

 males first mature, but based on the following tabulation, it appears 

 that this size is greater than 640 mm. t.l. : 



The smallest non-embryo examined was 227 mm. and the largest 

 embryo was 292 mm. The largest specimen seen was about 915 

 mm., but it seems probable that specimens reach approximately 

 1000 mm. Bigelow and Schroeder (1948) reported specimens of 930 

 mm., but whether these were R. terraenovae or R. porosus is not clear. 



Only one female with embryos was examined for precaudal vertebrae 

 counts. The female had 59 and the embryos 59 and 60. Three other 

 sibling embryos each had 60 precaudal vertebrae. 



Distribution and nomenclatural discussion. — Northeastern 

 coasts of North America from the Bay of Fundy south to Yucatan, 

 Mexico. The species was described from a specimen from Newfound- 

 land, but Jordan and Evermann (1896) and Bigelow and Schroeder 

 (1948) believe that this is in error and that the specimen is from the 

 southern United States (reasons not stated). No other specimens 



