126 A HISTORY OF RECENT CRUSTACEA 
Family 2.—Matutide. 
The characters are the same as in the Calappide, ex- 
cept that the third maxillipeds have the three terminal 
joints concealed beneath the triangular acute fourth joint. 
The family contains four genera. 
Matita, Fabricius, 1798, is regarded as the genus 
among the Brachyura in which the adaptation for swim- 
ming attains its highest: development. In the last pair of 
legs the oval terminal joint is supplemented by a very 
broad expansion of the preceding joint. Moreover, the 
other three pairs of legs are natatorial, having broad flat- 
tened joints, in particular the pair next the chelipeds evi- 
dently forming paddles of great power. Nevertheless, 
none of these limbs are fringed with hairs, the ordinary 
armature of swimming legs. The sufficient reason as- 
signed for this is that the crab’s safety often depends upon 
the extraordinary rapidity with which it can bury itself 
in the wet sand. Its flattened joints have sharp points 
and edges, with the digging powers of which any fringe 
of fur would seriously interfere. As it is, they can slip 
themselves under the sand in a moment, and before the 
troubled water has cleared over their departing footsteps 
the traces of them are smoothed and lost. Yet sometimes, 
it is said, their movements may be perceived under the feet 
of a person walking along the shore. Among the Japanese 
specimens of Matuta victor, Fabricius, de Haan observed 
some of what he calls ‘spurious females,’ but he mentions 
no peculiarities in them except their smaller size. If 
Paulson’s identification be right, the name of this species 
should become Matuta lunaris (Forskal.) 
Aepitus, Latreille, 1806, has, according to de Haan, 
the third joint much shorter than the fourth in the third 
maxillipeds, whereas in Matuta those two joints are equal 
in length. Hepatus princeps (Herbst) appears to be the 
proper name of the type species, which occurs both in the 
East and West Indies. This genus, and with it Osachila, 
