56 BULLETIN OF THE BUREAU OF FISHERIES 



Color. — Described as dark brown above, with or without darker blotches; 

 lower surface lighter to white. 



General range. — Formerly thought to be confined to the eastern Atlantic, off 

 the coasts of Europe and north Africa, and to the Mediterranean in rather deep 

 water, this shark has since been recorded from the Cape of Good Hope, the Pacific, 

 and from Australia. Apparently, however, it is rare everywhere, unless it be that 

 the rarity of capture is due to its habit of living at considerable depths. 



Occurrence in the Gulf of Maine. — A single specimen of this little known shark 

 came ashore at Provincetown in December, 1878, and this stiU remains the only 

 record of it from the western Atlantic. 



Habits. — Nothing is definitely known of its habits or whether it is a regular 

 inhabitant of the continental slope at and below 200 fathoms, as its wide distribu- 

 tion and proclivity for deep water suggests. 



SKATES AND RAYS 



Skates, with their disklike outlines, thin as a shingle, and their long tails, are 

 familiar objects along our shores. The Gulf of Maine supports four species in 

 great abundance, while several others have been recorded on rare occasions. So 

 far as the local fauna is concerned, this tribe falls into three groups — first, the 

 skates (family Rajidfe) with comparatively short tails and without spines; second, 

 the sting rays (families Dasybatidse and Myliobatidse) with long whipHke tails 

 armed with stiff spines; and third, the torpedo (family Narcaciontidae) , interesting 

 because provided with electric organs capable of giving a strong shock. All our 

 common species belong to the first group. 



Among skates and rays, as among sharks, fertilization is internal and the 

 modification of the posterior edges of the ventral fins into rodlike semitubular 

 claspers — the copulatory organs — distinguishes males from females at a glance. 

 Some families are viviparous; others lay eggs. 



The common skates look so much ahke that fishermen seldom discriminate 

 between them but speak of them all, large and small, simply as "skates." For 

 this reason we know very little about the individual differences in habits between 

 the several species. All, however, live chiefly on or close to the bottom, moving 

 through the water by undulations of the flexible pectoral fins, steering themselves 

 with the tail. All are decidedly omnivorous, feeding largely on the larger 

 Crustacea — shrimps, crabs, lobsters — as well as on mollusks, worms, etc., and to 

 a greater or less extent on fish. In the Gulf of Maine they are a nuisance, for they 

 bite the hook readily and often are caught in great numbers in otter trawls. To 

 give some idea of their abundance on the offshore banks I may note that the average 

 number of skates (all species together) taken on Georges Bank, per trip of 4 to 7 

 days, on 25 trips by several trawlers, January to December, 1913, was approximately 

 800, the largest catch being 4,521 skates, the poorest 82. Whether they are equally 

 abundant on Browns Bank is not clear, for though they are famiUar enough there, no 

 statistics as to the actual numbers caught are available. Skates are as plentiful 

 inshore as on the banks, as appears from the following representative catches on 

 long lines: 



