REPORT ON THE CRUSTACEA MACRURA. 



135 



falls, being attached by one angle : the moveable plate does not close as an operculum, 



but is inserted marginally, and both chamber and plate are fringed with rather long, 



finely ciliated, thickly-set hairs. At the foot 



of the appendage is a broad, flat, curved plate, 



thinly fringed with long hairs. The anterior 



extremity of this siagnopod reaches forwards 



beyond the base of the antennae ; it passes 



beyond the mandibles, and it is through this 



channel that the water of expiration passes 



out of the branchial chamber, the moveable 



plate at the extremity being probably a valve 



which admits of its more or less rapid egress. 



I have not determined the exact form of the 



mastigobranchial plate in this appendage, as it 



was partially ruptured. 



The first pair of gnathopoda is short, not 

 reaching beyond the mandibles, and seven- 

 jointed, but carries no ecphysis. The coxa is 

 short, the basis is scarcely more important, 

 and, without close observation, appears united 

 with it ; the ischium is short and cylindrical ; 

 the meros long, ovate, very slightly flexed, 

 concave below ; the carpos is transversely 



triangular, being broader at the propodal extremity than at the meral ; the 

 propodos is short, narrow and cylindrical, and the dactylos is reduced to a strong 

 slightly curved spine ; all the joints are fringed on the inner side with hairs, stiff 

 and firm on the propodos and carpos, soft, yielding, and ciliated on the meros and 

 ischium. 



The second pair of gnathopoda is as long again as the first, and reaches forwards as 

 far as the first joint of the antennae. It is long and slender, and consists of six joints. 

 The coxa is broad, and carries a rudimentary mastigobranchia, consisting of a minute 

 sharp-pointed membranous plate, supporting a few short hairs ; the basis and ischium 

 are fused into one long joint, arched on the outer side and flattened on the inner, and 

 longitudinally curved; the meros is long, and continues the arch of the previous joints ; 

 the carpos is cylindrical and short ; the propodos is also cylindrical and short, but longer 

 than the carpos ; the dactylos is lanceolate and thickly fringed with hairs, as is the 

 entire appendage, but more sparingly, with long ciliated hairs, mostly on the inner 

 side. 



The first pair of pereiopoda is as long as the animal, slender, flattened, and chelate. 



Fig. 32. — Third siagnopod, (maxillipede) of Polycheles 

 baccata. 1 outer, 2 inner surface. 



