SHORT-TAILED GROUP 3227 



teresting fact connected with them is their habit of living in association with other 

 animals; many species being found hiding between the shells of bivalve mollusks, 

 and they have also been discovered lodged in the interior of sea cucumbers. Enter- 

 ing this strange retreat in the zosea stage, they never quit it of their own choice. 



In the next tribe, Oxyrhyncha, the carapace is generally narrowed in front and 

 wide behind, and furnished between the eyes with a distinct beak, which is some- 

 times double and of great length. On its dorsal surface the carapace is usually 

 roughened with spines or tubercles, and frequently furnished with hooked hairs. 

 These crabs frequent deep water, and, at least, on the English coast, are regarded 

 by fishermen as spiders. The characteristics of this group are shown in the figures 

 of two British species, the thornback crab (Maia squinado} and the long-beaked 

 spider crab (Macropodia longirostris). Also belonging to this tribe is Macrochira 

 kcempferi, which is not only the largest crab, but the largest crustacean known. It 

 inhabits the seas of Japan, and is said to be able to span eleven feet with its out- 

 stretched pincers. 



A peculiarity of many of this group is their extreme untidiness, owing to the 

 quantities of seaweeds, zoophytes, and other marine objects affixed to the carapace 

 and limbs; and it has been ascertained that the presence of these extraneous 

 bodies is not the result of chance, but that they are placed there, presumably 

 for the purpose of concealment, by the crabs themselves. This feat they are 

 enabled to perform owing to the flexibility of their pincers, and to the hooked 

 hairs and spines with which the carapace is studded. Some examples of Hyas, 

 deprived of their covering of foreign bodies, were placed under observation in an 

 aquarium of which the bottom was covered with a layer of sponge. Contrary to 

 their habitual sluggishness of manner, the crabs appeared much perturbed, running 

 first to one side then to the other in the aquarium. Soon, however, by means of 

 their pincers they tore off small fragments of the sponges, and, after first putting 

 them to their mouths, placed them finally upon the dorsal surface of the carapace or 

 limbs, sticking them there with a rubbing movement. Sometimes after several vain 

 efforts the crab brought the fragment afresh to its maxillipedes and then repeated its 

 efforts to make it adhere. The animal persevered in these manoeuvres until the 

 piece of sponge remained fixed in the spot where it wished to place it. By contin- 

 uing to act in this fashion the crab succeeded in completely changing its appear- 

 ance, and in rendering itself indistinguishable among the objects that surrounded it. 

 The crab proceeded in exactly the same fashion when the bottom of the aquarium 

 was strewn with seaweeds or any kind of zoophytes. Moreover, it was observed 

 that some specimens, clothed with seaweed, which were left in an aquarium of 

 which the bottom was covered with sponges did not hesitate to take off their old 

 clothing and put on a new one of sponges. 



The present tribe also contains the family Parthenopidcz , the species of which, 

 although not armed with spines and hooked hairs for holding foreign objects, are 

 yet protected in the midst of their surroundings, by having the carapace covered 

 with pits and variously shaped depressions, giving it a roughened corroded appear- 

 ance, and consequently imparting a resemblance to pieces of rock or fragments of 

 dead coral. 



