SHARKS AND RAYS OF BEAUFORT, NORTH CAROLINA. 267 



Family GALEORHINID^. The smooth dogfishes. 

 Genus GALEORHINUS Blainville. 

 18. Galeorhinus laevis Valmont. Whipper-tail; dogfish; smooth dogfish. 



Mustelus canis. Smith, 1907. p. 32: Coles, 1914, p. 89. 



Teeth. — Teeth small, numerous, pavementlike, anterior base of tooth slightly ridged; upper teeth 

 witli a short, blunt cusplike projection on posterior margin; lower teeth similar in form, cusp less 

 prominent, absent from teeth near angles of mouth. No sexual differences were noted between the teeth 

 of a male 75 cm. long and a female gi cm, long from Cape Lookout. 



Denticles. — ^The denticles are large (the larger ones in a specimen 90.8 cm. long being 0.4 mm. long 

 by 0.3 mm. wide), tmequal in size, overlapping, ovate in outline, with 2 to 4 short, low, nearly parallel 

 keelson basal portion of denticle; the length and prominence of the keels vary; rarely do they extend to 

 the apical margin; apex acute; pedicel small, relatively high; base small. 



Fig. 19. — Denticles, Galeorhinus tcnis, 91 cm. Ions, from Cape Lookout, N. C. 



The laboratory has no record of the capture of examples of this species in Beaufort Harbor. It is 

 abundant at Cape Lookout in the spring, but is rarely seen later than June. Individuals left by the 

 fishermen, are common on the beaches at Cape Lookout in April. It is locally known as " whipper-tail. " 



Family SQUALIDjE. The spiny dogfishes. 

 Genus SQUALUS Linnaeus. 

 19. Squalus acanthias (Klein). Spiny dogfish. 



SqtuUus acanthias, Gudger, 1912, p. 143; id., 1913b, p. 98; Coles. 1914, p. 92. 



28 



Teeth. — Teeth in — rows, regular in arrangement, similar in form in each jaw; upper smaller than 

 23 

 lower; cutting edges transverse, nearly horizontal, ending posteriorly in a small, sharp-pointed cusp, 

 below this a deep notch and a prominent basal shoulder; on basal portion of tooth there is a narrow median 

 lobe of enamel, outline of base more or less concave on each side of this projection. Cutting edges of 

 upper teeth more oblique than the lower, the cusps being more erect; two rows of teeth ftmctioning. 



Denticles. — The denticles are large, being about 0.46 mm. long by 0.32 mm. broad in a shark 84.5 cm. 

 long; a high median keel widest on basal portion of denticles and projecting beyond basal margin; a low 

 keel along each margin normally present; apical margin tridentate, median lobe prominent; pedicel 

 stout; base large, stellate. 



At Cape Lookout, Coles states that this species is very abundant in April and the first week of May. 

 Only a single example, taken May 23, 1907, has been recorded from Beaufort Harbor. This was a female, 



