VI 



OXYSTOMATA RESPIRATORY MECHANISM-^ 



187 



the chelipedes properly in position. The inhalant openings are si t u- 

 ated just in front of the chelipedes. It is a most remarkable fact 

 that among the Cyclometopa, Lvpa hastata(Fig. 131)has an exactly 

 similar arrangement. Apparently we have here another instance 



KM;. 129. Dorsal view of Alutntn imnksii, x I. (From an original drawing 

 prepared for Professor Weldou.) 



of convergence, similar to that of Corystes and ^///<///"v, but the 

 case is complicated by the fact that some of the Oxystumata, and 

 among them Mufnta, show a certain amount of relationship ID 

 the Cyclometopous Port un ids, so that it is just conceivable tliat, 

 the resemblances in the respiratory arrangement an- due to a 

 com i in in descent and not to convergence. 



In the Leucosiidae, of which the Mediterranean lli<t nucleus 

 (Fig. 11-50) is an example, the inhalant aperture is situated bet \\een 

 the orbits, and leads into gutters excavated in the "pterygo- 

 stomial plates" Hanking the mouth, which are furnished with 

 filtering hairs and are converted into closed canals by expansions 

 of the cxopodites of the t bird maxillipedes. Thus these Crabs 

 possess a lilt.ering apparatus independent of ihc chelipedes and D|' 

 the margin of the carapace. 



Fam. 1. Calappidae. (.Vphalothorax rounded and crab like. 

 The abdomen is hidden under the thorax, the antennae are 

 small, and the legs normal in position. The all'ercnt opeiiii. 

 to tin: gill-chambers lie in front, of the chelipedes. Male open- 

 ings on coxae of last pair of le-s. (',//<//,/( (I-'ig. iL'S; cireum 



