BY DAVID G. STEAD. 751 



have sketched them. The flabellum is here a long somewhat 

 oblong-ovate plate, fringed with hairs of the same nature as those 

 before described (Fig. 1, G). The gill in this case is almost 

 rudimentary (Fig. 1, A, R.Br.). It is quite obvious that even if 

 the gill were fully developed on this podobranchia, it would be in 

 the way, as this part has to move freely up and down, so the 

 reason for its aborted condition is plain. 



The flabellum of the second maxillipede, though serving a 

 similar purpose to that of the third maxillipede, being very much 

 shorter, and having to undergo far less movement, does not 

 interfere with the accompanying gill, which, originating from its 

 base, scarcely passes through any motion at all. The flabellum 

 of the third maxillipede sweeps the internal faces of the four 

 posterior branchise, and the adjacent portion of the wall proper 

 of the thorax. As will be observed by referring to the diagram, 

 the basal portion of the flabellum is devoid of the fine hooked 

 setae which characterise the remainder of it This being so, the 

 "brush " misses just in that one place. In several specimens in 

 my possession, parasites, in the shape of tubicolous annelids, have 

 taken advantage of this and have grown there undisturbed. 

 This, of course, helps to prove that, were it not for these flabella 

 the sills and walls of the branchial chamber would soon become 

 clogged with parasites or dirt. Perhaps I may mention that not 

 infrequently I have observed specimens in which the chelipedes 

 and the subhepatic and pterygostomial regions also harbored 

 parasitic annelids. 



Branchial arrangement.— This is the same as that of Cancer 

 pagurics'^'', with the exception that the gill portion of the 

 podobranchia of the third maxillipede is relatively far smaller, 

 and in fact can scarcely be said to be more than rudimentary. 

 The inner surface of each gill is clothed with short bi'istly hairs, 

 which are here, perhaps, as an additional pi-otection against 

 parasites. 



*" The Craylish," Huxley, p. 277. 



