474 APPENDIX II 



common round-bodied spider-crabs of the eastern coast of the 

 United States. The largest (Chionoecetes opilio) has a rough, 

 flattened back, semicircular behind and narrowed in front, with 

 a short bifid beak and very long, flat legs armed with small spines. 

 This crab attains a large size, sometimes having a span of over 

 two and a half feet, with the shell itself five inches in width. The 

 smaller species are much alike, and are known as toad-crabs, from 

 a fancied resemblance to that batrachian ; their shells are two or 

 three inches long, shield-shaped, one having lateral wings on the 

 forward half (Hyas coarctatus) , while the other has not (Hyas 

 araneus) ; the beak is short and broad, and split through the 

 middle. Like most of the family to which they belong, they 

 have the habit of attaching to their backs foreign substances, like 

 seaweed, bryozoans, and sponges, which are held in place by 

 hooked hairs on the surface of the crab. In this way the carapace, 

 and the legs also, may become entirely hidden by a miniature 

 forest which serves to protect the crab from its enemies. Never- 

 theless, many individuals find their way into the stomachs of 

 fishes. This is true not only of crabs and shrimps, but of smaller 

 crustaceans, such as schizopods and amphipods, which are con- 

 sumed in great quantities by cod and other large fish as well as by 

 whales and shore-birds. 



Only two hermit-crabs are known on the coast, but in favourable 

 spots they are abundant from low-water mark to perhaps fifty 

 fathoms. They are quite different in appearance and behaviour 

 from true crabs. The eyes are not incased in sockets or orbits, 

 the antennae are long, the claws are very unequal in size, the 

 right (in these species) always the larger, and the walking legs 

 are four in number. The hinder part of the body is soft, tapering, 

 and asymmetrical, as it has to accommodate itself to the shape of 

 the gasteropod shell which forms the crab's dwelling. Each indi- 

 vidual appropriates a dead shell, and is never seen without it 

 except when the increasing size of the inmate compels it to seek a 

 larger tenement. The transfer from one shell to another is made 

 with striking rapidity, the little creature being very active and 

 wary and on the lookout for its stronger enemies. Although it 

 crawls about with the body covered by the shell, and the limbs 

 extruded, yet it is capable of retreating entirely into its domicile 

 and closing the aperture with its claws. The two Labrador species 

 are very similar ; one (Pagurus pubescens) has claws covered with 

 stout spines and with hairs which retain particles of mud and sand, 

 while the claws of the other (Pagurus krtfyeri) are rough, with finer 

 and more numerous spines, and are almost devoid of hair ; there is 

 a difference, too, in the shape of the left or smaller claw : the outer 

 surface of the prismatic hand-joint is narrow and lanceolate in 



