770 NATURAL HISTORY OF AQUATIC ANIMALS. 



tide-pools. They were never found concealed beneath the rocks, where, however, irroratus 

 abounded. It is a much heavier and more massive species than the irroratus, and is consequently 

 much better adapted than that species to the situations in which it is found. So many individuals 

 falling a prey to birds is evidently a result of the habit of remaining exposed between tides, 

 although the heavy shell must afford much greater protection than the comparatively fragile 

 covering of irroratus would afford to that species if similarly exposed. The borealis was also 

 found at a somewhat similar locality, but more exposed to the sea, on Eam Island Ledge, a low 

 reef open to the full force of the ocean. One specimen of moderate size was dredged in the ship 

 channel between Peak's Island and Cape Elizabeth, in ten fathoms, rocky and shelly bottom, and 

 specimens were several times captured in lobster-traps, set at a depth of eight or ten fathoms, 

 among rocks. Specimens were also several times found in stomachs of the cod taken on the cod 

 ledges. 



"In the vicinity of Vineyard Sound, this species was not infrequently found thrown upon 

 sandy beaches, but never upon beaches very far removed from rocky reefs. The following are 

 the localities where it was seen in greatest numbers: Along the sandy beach of Martha's 

 Vineyard, from Menemsha Bight to Gay Head; the rocky island of Cuttyhunk; and the rocky 

 outer shores of Neman's Land, where dead specimens were found in considerable abundance. In 

 the vicinity of Noank, Connecticut, it was occasionally found dead upon the shores, and was 

 several times obtained from lobster-traps. 



"The largest specimens I have seen are two males, of almost exactly the same size, one from 

 Oasco Bay, the other from near Koank, Connecticut. The carapax of the specimen from Casco 

 Bay is three and one-half inches long and five and three-fourths inches broad." 



Economic value. — Cancer borealis is supplied to the Newport markets in small quantities 

 during most of the summer months, and is much esteemed there as food, being considered by 

 many preferable to the Blue Crab (Callinectes hastatm). It is taken by the fishermen on the shore 

 and in shallow water. 



Name. — The term " Jonah Crab," which we have adopted here for this species, is the one by 

 which it is commonly known in and about Narragansett Bay, Rhode Island, and to some extent 

 also about Vineyard Sound, Massachusetts, but apparently not elsewhere. The origin of the 

 name we have not been able to ascertain. In most localities where it occurs it is confounded by 

 the fishermen with the commoner Rock Crab. 



The Common ceab op the Pacific. coast — Cancee magisteb, Dana. 



This is the largest of the edible species of Crabs of the Pacific coast of the United States, and 

 likewise the most important. It is the only species commonly eaten in San Francisco, although 

 two other species inhabiting the same region, and which are described farther on (Cancer productus 

 and Cancer antennarius), are also edible and of good flavor. The carapax of adult males usually 

 measures from seven to nine inches in breadth and four to five inches in length; the females 

 average much smaller. The color of the upper surface is a light reddish-brown, darkest in front; 

 the limbs and under surface are yellowish. The anterior margin of the carapax forms a nearly 

 regular elliptical curve, reaching back to about the middle of the sides and interrupted by nine 

 slightly prominent, sharp teeth on each side. At the termination of this curve on each side, there 

 is a strong, pointed tooth, projecting directly outward, and forming the commencement of the 

 postero-lateral margins, which are long and slope abruptly backward so as to leave but a narrow 

 posterior margin. The surface of the carapax is slightly convex, undulated, and covered with 

 papillae; the claws are strongly toothed above and ribbed at the sides. 



