SHARKS AND RAYS OP BEAUFORT, NORTH CAROLINA. 255 



In the largest example the distal margin of the first dorsal was deeply concave; second dorsal large, 

 similar in shape to the first; pectoral short, broad, distal margin slightly concave; anal similar in form 

 to second dorsal but much smaller. Labial fold short. 



In smallest example the liver was very large, more than half the length of the body; 400 cc. of bile 

 in gall bladder; stomach empty except for bait, spiral valve as in Scoliodon ierrcE-novce; heart small, 

 ventricle 6.1 cm. from apex to base, width at base 5.7 cm., length from apex to insertion of conus6.6cm. 

 The red corpuscles of the blood were 16 ju by 12.4 m, somewhat irregular in outline, but generally oval; 

 the white corpuscles had an average diameter of 8.8 ju. 



Color at death. — Ground color of back dark bluish-gray, lemon-yellow tinge below, shading into 

 white on belly ; fins grayish except the anal, which was yellowish edged with gray ; claspers white ; 

 margins of gill openings white, shading to dark gray, with an intramarginal area above and below white; 

 eye yellow-gray, pupil black; interior of mouth white. 



The toadfish (Opsanus tau) proves a very effective bait for sharks. If hooked carefully through 

 the jaws it will live for several days, and is immune to attacks from crabs and other fishes. 



Among the fishes recorded by Linton (1905, p. 339) is Carcharhinus obscurus of which he says: 



" These sharks are referred to this species although they do not agree in all diagnostic features with 

 the descriptions published in Jordan and Gilbert's Fishes of North America or Jordan and Evermann's 

 later work. The pectorals do not reach quite to the first dorsal. The second dorsal is larger than the 

 anal. There is not much difference between the upper and lower teeth. They agree rather with 

 Prionace in the character of the fins, but the nose is much shorter and broader than in that genus." 

 With the exception of the one caught by Coles on July 26, 1902, these appear to have been examples 

 of H. brevirostris. The short pectorals, second dorsal larger than anal, similarity of teeth in each jaw, 

 and the short and broad snout are characters which are more diagnostic of this species than any other 

 found in tliis region. 



From recent data the species appears to be fairly common in the Beaufort region and has undoubt- 

 edly been confused with other species by earlier writers. The writer has been unable to obtain an 

 authentic record of the presence of C. obscurus in this region. 



Genus CARCHARHINUS Blainville. 



KEY TO Tue SPECIES. 



a. Fins black-tipped; teeth similar in form in both jaws, narrow-cusped, broad-based in ^^ rows; 



30-31 

 dermal denticles small, imbricated, three-keeled in small examples, five to seven keeled in large 



ones; snout elongate limbatus. 



aa. Finsnot black-tipped; teeth in upper jaw triangular, notched or not; cuspsoflowerteethnarrow, erect. 

 6. Dermal denticles three-keeled, not closely imbricated without or with distinct apical lobes; upper 

 teeth narrowly triangular, longer than broad, without distinct basal shoulders, in 29 to 31 rows; 

 lower teeth narrow-cusped in 27 to 30 rows; snout short, broad, blunt, its length slightly greater 

 than distance between angles of mouth; pectorals broad, breadth 1.7 times length, without promi- 

 nent lower lobe milberii. 



hb. Dermal denticles five-keeled, closely imbricated, upperteeth deeply notched or broadly triangular. 



26 

 c. Snout elongate, moderately pointed; teeth in — ^ — rows; upper teeth deeply notched; lower 



teeth short, very narrow-cusped acronotus. 



cc. Snout short, broad, blunt, its length less than distance between angles of mouth; teeth in ?il3i 



26-32 



rows; upper teeth broadly triangular, broader than high; cusps of lower teeth rather broad; 



pectorals long, narrow, twice as long as broad, with a prominent basal lobe commersonii. 



11. Carcharhinus limbatus (MuUer and Henle). 



Carcharhinus obscurus, Linton. 1905, p. 339 (in part). 

 Carcharhinus timbaius. Gudger, 1913a, p. 2; Coles. 1914, p. 90. 



Teetk. — Teeth in ' rows, erect, subulate, narrow-cusped, broad-based; cusps of upper teeth finely- 

 serrate, basal shoulders finely denticulate; cusps of lower teeth normally with small serrations, bases 

 smooth; two to three rows of small teeth at symphysis of each jaw. 



