284 MARINE INVERTEBRATES 
FaMILy MAIIDE 
The members of this family are known as “spider-crabs.” 
Their bodies are thick and more or less round in form, narrowing 
in front to along, beak-like projection. The surface is generally 
rough and irregular, having tubercles, spines, prickles, and hairs. 
The legs are long. These crabs are often covered with seaweeds, 
hydroids, and other organisms, which they gather with their long 
and flexible chelipeds and place upon their backs, presumably to 
conceal themselves from their enemies. They seem to select, 
instinctively or with reason, such things as will bear transplant- 
ing, sometimes using sponges and polyps which are not destroyed 
by being torn apart, and they also select their dress with refer- 
ence to its masking uses. A Hyas covered with bright-colored 
algee was seen to remove them and replace them with sponges, 
when transferred to the locality of the latter, where the 
former did not grow. The animal takes in his claw the object 
he has gathered, and first holds it to his mouth, where it is 
moistened with a secretion of mucus or cement, and then places 
it on his back. If it does not hold, the operation is repeated, 
often several times, a new spot on the shell being selected each 
time. It has also been found that the coats of these crabs are 
covered with hairs which are differently arranged in different 
genera, some being hooked, others serrated, ete., and that 
these aid in holding the transplanted organisms in place. The 
crab is sometimes so covered with these growths as to be entirely 
concealed beneath them. It is a sluggish animal, and inhabits 
shallow water along the whole of the Atlantic and Pacific coasts 
Genus Libinia 
L. dubia, L. emarginata. These two species inhabit the Atlantic 
coast, and are found on muddy shores and flats, among decaying sea- 
weed, in eel-grass, and even beneath the surface of the mud. They are 
covered with hairs, and sometimes have planted on their backs alge, hy- 
droids, and even barnacles. The legs of L. emarginata often spread a foot 
ormore. The malesare much larger than the females. The species ranges 
from Maine to Florida. JZ. dubia does not extend north of Cape Cod. 
It is found more commonly than L. emarginata in very shallow water 
