HABITS OP THE JONAH CRAB. 769 



normal ones. The antennro and ambulatory legs are proportionally longer than in tbe adult. The 

 young Crabs in this stage were once or twice taken in the towing-uet, but they were not common 

 at the surface, although a large number were found, with a few in the megalops stage, among 

 hydroids upon a floating barrel in Vineyard Sound, July 7." 1 



THE JONAH CEAB CANCER BOREALIS, Stimpson. 



AFFINITIES. The " Jonah Crab " is very closely related to the common Rock Crab, and is 

 also to some extent associated with it in its distribution. The two species are so much alike in 

 shape and general characters that they were originally regarded as the male and female respect- 

 ively of one and the same species. They are, however, quite distinct, and after the differences 

 have been once noticed there is no difficulty in distinguishing between them. The Jooah Crab 

 differs from the Rock Crab in the much larger size of adult specimens, in the rougher surface of 

 the carapax and claws, caused by the larger grannies covering it, which are of irregular size, some 

 being much larger than others, and by the serrations of the antero- lateral margins being crenate 

 and the posterior ones armed with numerous sharp points, instead of being simple as in the Rock 

 Crab. The legs of the Jonah Crab are also proportionately shorter and heavier than those of 

 the Rock Crab. The color of Cancer borealis is yellowish beneath and brick-red above, the limbs 

 corresponding more or less in coloration with the lower surface, but of a light reddish tint above. 



DISTRIBUTION AND HABITS. Besides being found in moderately deep water, the Jonah Crab, 

 in certain localities, inhabits the rocks near low-tide level, in the clear waters of the ocean shores, 

 but it never occurs in muddy or sandy bays and harbors where the Rock Crab abounds. The 

 rauge of Cancer borealis is from the eastern end of Long Island Sound to Nova Scotia, but it is 

 not found everywhere within these limits, being apparently local in its distribution and abundant 

 only within certain more or less restricted areas. The principal localities where it has been 

 observed are as follows: off Noaiik, Connecticut; off Watch Hill and Newport, and in Narra- 

 gansett Bay, Rhode Island; Vineyard Sound, Neman's Land, and Salem, Massachusetts ; Casco 

 Bay, Maine ; Bay of Fundy and Nova Scotia. In 1SSO, the United States Fish Commission found 

 the Jonah Crab abundant everywhere in the lower part of Narragausett Bay from about low-tide 

 level down to the greatest depths of the bay, and it was likewise very common off the bay, and 

 oft' the north end of Block Island. The following account of the habits and distribution of this 

 species is taken from Prof. S. I. Smith's account: 2 



"In habits this species differs very greatly from irroratus. The best opportunities which I 

 have had for observing it were at Peak's Island, in Casco Bay, August 'and September, 1873. 

 Empty carapaces, chelipeds, etc., of borealis were at first found in abundance scattered along the 

 outer shores, far above the action of the waves, where they had evidently been carried by gulls 

 and crows, and were also found in considerable numbers half a mile from the shore, in a forest of 

 coniferous trees thickly inhabited by crows. For several weeks no living specimens of borealis 

 were discovered, although the irroratus was found living in abundance all about the island, 

 without, howe% T er, its remains scarcely ever being found scattered about with those of borealis. 

 The borealis was finally discovered in abundance at low water on the exposed and very rocky 

 shores of the northern end of the island. At this locality, between eighty and ninety specimens, 

 all females and many of them carrying eggs, were obtained in a single morning. They were all 

 found in situations exposed to the action of the waves, and were either resting, entirely exposed, 

 upon the bare rocks and ledges, or clinging to the seaweeds in the edge of the waves, or in the 



1 S. I. Smith, Vineyard Sound Report, pp. 530-533, 1871-'72. 

 "Trans. Conn. Acad., v, p. 40, 1879. 

 49 F 



