74 A Guide to the Zoological Collections in the 



swimmers. All of the four families into which the tribe 

 is subdivided are numerously represented in the Gallery. 

 1st Family, Calappidse. — In Calappa the carapace is 

 extended on both sides to form an arched 

 shield which completely roofs over the last four 

 pairs of thoracic legs, while the first pair of 

 thoracic legs, or chelipeds, are themselves ex- 

 panded upwards to form when flexed a front 

 shield for the body. In Miirsia the lateral 

 prolongations of the carapace form great 

 protective spikes. Examples of both of these 

 forms are shown in Case 68, 

 2nd Family, Matutidse. — In Matuta all the legs, except 

 the chelipeds, are modified to form paddles for 

 swimming. Matuta is one of the commonest 

 shallow-water crabs of the Indian Seas. 

 3rd Family, Leucosidse. — A large family, most of the 

 members of which are small and timid, and 

 live concealed in the mud of the sea-bottom. 

 Many of them have the carapace beautifully 

 sculptured, the sculpturings in Oreophoriis 

 giving the animal a deceptive resemblance to 

 the coral shingle in which it lives. Specimens 

 of the following Indian genera are shown — 

 Philyra, Myra^ Myrodes, Parilia, Randallin, 

 Leucosia, Nursia ^Lithadia, Ixa, Iphis, Oreo- 

 phoriis. 

 4th Family, Dorippidae. — The last pair or last two 

 pairs of legs are very small, and they spring 

 from the dorsal surface or back of the cephalo- 

 thorax and end in sickle-like claws. In these 

 claws is often held, as in a frame, a valve of a 

 mollusk shell which the crab carries as a roof or 

 shield. The upper surface of the shell is 

 usually taken possession of by a sea-anemone, 

 the sea-anemone furnishing an additional pro- 

 tection to the crab which the crab repays by 



