342 Memoir Sears Foundation for Marine Research 



itself to fresh water and developed a local race (see under C. nicaraguensis, p. 381). 

 On the other hand, it rarely shows itself at the surface, as the more pelagic members of 

 the genus commonly do, unless lured up by the scent of food, such as floating offal. We 

 have never heard of one jumping, whether at liberty or after being hooked. 



Under natural conditions its diet is perhaps no less varied than that of the Tiger 

 Shark (p. 270). Thus the stomach contents of a series taken off North Carolina in 

 summer have been reported as including crabs, smaller sharks that had been taken in 

 the same net, the fin of a porpoise which was probably obtained in the same way, shad 

 (Alosa) and mackerel. That they had eaten the last-named proves that they have a 

 greater ability to capture fast-swimming fishes than their rather sluggish habits would 

 suggest. Also found in the stomach were large pieces of devil-rays {Mobula), which, 

 when fitted together, showed the victim to have been bitten into five parts. It also attacks 

 sting-rays in Florida waters, as evidenced by a spine imbedded in one's mouth. It is 

 notorious also as a scavenger, devouring any kind of offal, and it bites readily on almost 

 any large bait of fish or meat. 



Females with embryos nearly ready for birth have been taken in Florida in October, 

 January and February, which suggests that the young are born there in late winter and 

 early spring, but beyond this nothing is known of the breeding habits. 



Relation to Man. The only commercial importance of this species is that it con- 

 tributes something to the general catch of sharks around Florida. But no data are available 

 to show its importance relative to other species. Like various other sharks it has been 

 named a man-eater, but we think it unlikely that this reputation is deserved, for other- 

 wise shark fatalities probably would be far more frequent than they actually are in 

 Florida and the West Indies, where it is one of the more common of the larger sharks. 



Range. In the western Atlantic from southern Brazil to North Carolina and occa- 

 sionally north to the vicinity of New York. It is not yet certain whether leucas occurs at 

 all in the eastern Atlantic. It is true that sharks have been recorded under that name from 

 tropical West Africa and from Algeria, but the first of these reports was by name only," 

 while the brief description accompanying the second" would apply equally well to any 

 other Carcharhinus with moderately blunt snout, for example, longimanus, milberti or 

 obscurus. The commersonii described by Rey^^ from the coast of Spain was doubtless an 

 obscuruSy for it had a mid-dorsal ridge and agreed with that species in other respects as 

 well. Nor is any Carcharhinus other than longimanus included in the most recent survey 

 of the fishes of Portugal.^* 



Occurrence in the Western Atlantic. Published accounts are in line with word-of- 

 mouth reports to the effect that leucas is a tropical species, expanding its range northward 

 during the warm months and perhaps southward as well. But it is not yet possible to 



26. Rochebrune, Act. Soc. linn. Bordeaux, (4) 6, 1882: 42; Metzelaar, Trop. Atlant. Visschen, 1919: 187. 



27. Guichenot, Explor. Alger., .?, Poiss., 1850: 124; a specimen sent to Paris (Dumeril, Hist. Nat. Poiss., j, 1865: 



358). 

 »8. Fauna Iberica Peces, /, 1928: 342, 343. 29. Nobre, Fauna Marinha Portugal, t, 1935. 



