448 APPENDIX II 
common round-bodied spider-crabs of the eastern coast of the 
United States. The largest (Chionecetes 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 antenne are long, the claws are very unequal in size, — the 
right (in these species) always the larger, —and the walking legs 
are fourin 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 krg@yeri) 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 
