VI OXYSTOMATA—RESPIRATORY MECHANISMS 187 
the chelipedes properly in position. The inhalant openings are situ- 
ated just in front of the chelipedes. It is a most remarkable fact 
that among the Cyclometopa, Lupa hastata(Fig. 131) has an exactly 
similar arrangement. Apparently we have here another instance 
Fic. 129.—Dorsal view of Matuta banksit, x 1. (From an original drawing 
prepared for Professor Weldon.) 
of convergence, similar to that of Corystes and Albunea, but the 
case is complicated by the fact that some of the Oxystomata, and 
among them J/atuta, show a certain amount of relationship to 
the Cyclometopous Portunids, so that it is just conceivable that 
the resemblances in the respiratory arrangement are due to a 
common descent and not to convergence. 
In the Leucosiidae, of which the Mediterranean //ia nucleus 
(Fig. 130) isan example, the inhalant aperture is situated between 
the orbits, and leads into gutters excavated in the “ pterygo- 
stomial plates” flanking the mouth, which are furnished with 
filtering hairs and are converted into closed canals by expansions 
of the exopodites of the third maxillipedes. Thus these Crabs 
possess a filtering apparatus independent of the chelipedes and of 
the margin of the carapace. 
Fam. 1. Calappidae—Cephalothorax rounded and crab-like. 
The abdomen is hidden under the thorax, the antennae are 
sinall, and the legs normal in position. The afferent openings 
to the gill-chambers lie in front of the chelipedes. Male open- 
ings on coxae of last pair of legs. Calappa (Fig. 128) circum- 
