()8 Guide to Crustacea. 



Tablc-cubc of the genus I'Jbalui. They arc small Crabs, reseuibliiig the pel^hles 



No. 13. among which they are found. Specimens of Ebalia tuhcrosa are 



shown in their natural surroundings in Wall-case No. 11. 



In the family Dorippidae the afferent branchial openings are 

 in front of the bases of the chelipeds. The abdomen is not com- 

 pletely concealed under the cephalothorax. The last two pairs of 

 legs are elevated on the dorsal surface of the body, and liave the 

 terminal segments more or less distinctly modified to form a pre- 

 hensile claw. The Dorippidae appear to have given up the sand- 

 burrowing habits characteristic of other Oxystomata, and they 

 conceal themselves by holding a piece of sponge or some other 

 object over, the back by means of the hinder legs. Many of the 

 species inhabit the deep sea. 



In the Baninidac the water seems to enter the branchial 

 chamber from behind, between the edge of the carapace and the 

 bases of the last pair of legs. As in Dorippidae, some of the 

 abdominal somites are visible from above, and the last pairs of legs 

 are elevated on the dorsal surface. The legs, however, are flattened 

 and paddle-like, and appear to be used for swimming and digging, 

 as in Matuta. The "frog-crab," Banina scabra, is, in general 

 appearance, one of the most striking and aberrant of the Brachyura. 

 Table-case In the Tribe OxYRHYNCHA the carapace is usually triangular in 

 shape, narrowed in front, and produced to form a rostrum. The 

 mouth-frame is square. The genital ducts of the male open on 

 the bases of the last pair of legs. As a rule, the legs are long and 

 slender. 



The Crabs of this tribe are generally sluggish and inactive 

 animals, and many of them, as already mentioned, have the habit 

 of masking themselves with seaweed, sponges, etc. This habit is 

 illustrated by some of the preparations in Wall-case No. 6, and 

 evidences of it will be noticed on many of the specimens in this 

 case. 



The members of the family Maiidac are known as " Spider- 

 crabs." In these, the chelipeds are very mobile, and are usually 

 not much stronger than the other legs. The orbits are more or 

 less incomplete. Among the specimens exhibited may be men- 

 tioned Macropodia longirostris, a common British species which 

 has the long and slender legs that are typical in the group. 

 Hnenia protcus is noteworthy for the leaf-like expansions of the 

 carapace ; in life it is of an olive-green colour and is difficult to 

 detect among the foliaceous sea-weeds which it frequents. To 

 this family belongs the large Spider-crab of the South and West 



No. 14. 



