34 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



a practical role of any moment among the smaller 

 fish. Further south, however, and wherever it 

 is numerous in the Atlantic, it makes itself a pest, 



tangling and tearing mackerel nets as well as 

 destroying and chasing away the more valuable 

 fishes on which it feeds. 



CAT SHARKS. FAMILY SCYLIORHINIDAE 



Distinctive features of these little sharks are 

 that they have five pairs of gill openings and an 

 anal fin; that at least one-half of the base of the 

 first dorsal fin is rearward of the point of origin 

 of the pelvic fins; that the front margin of the 

 nostrils does not bear a fleshy barbel; and that 

 they lay eggs with horny shells and tendrils at 

 the corners. Many species are known. The 

 familiar spotted dogfishes of European seas (two 

 species) fall in this group. And one species calls 

 for mention here. 



Chain dogfish Scyliorhinus retifer (Garman) 

 1881 



Description. — The chain-like pattern of narrow 

 black stripes with which the reddish-brown back 

 and sides of this little shark are marked are so 

 distinctive that there is no likelihood of confusing 

 it with any other shark. We need only add that 

 its first dorsal fin stands wholly behind the rear 

 ends of the bases of its pelvic fins; that its second 



dorsal fin is about one-half as large in area as its 

 first dorsal fin; that its tail fin is square-tipped 

 and occupies only about one-fifth of the length 

 of the fish; and that its teeth are similar in the 

 two jaws, narrow-triangular with a small second- 

 ary cusp on either side. 



Size. — The largest specimen measured so far 

 was 17 inches long. 



General range and occurrence in the Gulf of 

 Maine. — The range of the chain dogfish is con- 

 fined to the 40-125 fathom zone between the 

 offings of Cape Lookout, North Carolina, and of 

 Nantucket. It seems to be the most plentiful off 

 Virginia, in the general offing of Chesapeake Bay, 

 where considerable numbers are taken during the 

 winter trawl fishing. They are caught now and 

 then as far as the offing of Marthas Vineyard, 

 and Cap'n Bill II trawled one, in July 1952, south 

 of Nantucket Lightship, Lat. 40°02' N; Long. 

 69°37' W, at 75-90 fathoms which brings it within 

 the arbitrary boundary of the Gulf of Maine. 



Figure 9A. — Chain dogfish (.Scyliorhinus retijer), male, about 17 inches long, New Jersey. After Bigelow and Schroeder. 



SMOOTH DOGFISHES. 



These are rather small sharks, with two dorsal 

 fins without spines, the second dorsal (in Atlantic 

 species) nearly as large as the first, and they have 

 an anal fin. The tail fin is very strongly asym- 

 metrical, its lower anterior corner forming a low 

 but rather definite lobe in some, but not in others. 

 The teeth are small, with several rows in function 

 imultaneously, flat, and pavement-like in some, 



FAMILY TRIAKIDAE 



but with three or four definite cusps in others. 

 The eye has no nictitating ("winking") mem- 

 brane, but only a longitudinal fold along the 

 lower eyelid. They resemble the requiem sharks 

 (Family Carcharhinidae, p. 36), except for the 

 teeth, and for the lack of a nictitating membrane. 

 Only one species is known from the Gulf of Maine, 

 or is ever likely to be found there. 



Smooth dogfish Mustelus canis (Mitchill) 1815 



Smooth dog; Smooth hound; Grayfish 



Bigelow and Schroeder, 1948, p. 244. 



Garman, 1913, pi. 4, figs. 6-9, as Galeorhinus laevis. 



