836 THE VOYAGE OF H.M.S. CHALLENGER. 



" First Maxillie with the inner lAatQ tolerably large, apically furnished with two setae, 

 sometimes plumose ; the palp two-jointed, carrying narrow spines on the apex. 



" Second Maxillae with the plates very short and broad, the inner broader than the 

 outer. 



" Maxillipeds with the inner plates small ; the outer plates sometimes longer, 

 sometimes shorter, never very large, armed on the inner margin with strong spines 

 increasing as they approach the apex ; the palp broad and robust ; its last joint strong, 

 unguiform. 



" The body little compressed. The back round, rarely carinate or armed with teeth. 

 The side-plates of moderate size, setose on the lower margin. The first side-plate apically 

 dilated. The head generally produced in front into a broad rostrum, on which the eyes 

 are placed. For the rostrum to be absent and the eyes placed on the sides of the head 

 is rare. 



" Upper Antennse without accessory flagelium. 



" First and Second Gnathopods with the hand more or less strong, either subcheli- 

 form or cheliform ; the Second Gnathopods rarely without a subcheliform hand ; in each 

 pair the wrist generally strongly produced into a process (calx) on the lower hinder 

 angle. 



" Third and Fourth Perseopods almost alike in size and shape. 



" Fifth Perseopods elongate, very often twice as long as either of the two preceding- 

 pairs. 



" Uropods elongate, biramous ; the third pair with the rami narrow ; the peduncle 

 seldom elongate. 



" Telson short, undivided." 



Schneider, in his valuable review of the characteristics of the family Oediceridse, lays 

 especial stress on the last joint of the Fifth Perseopods, which is not nail-like but quite 

 straight, cylindrical, about as long as the preceding joint, armed with spinules and some- 

 times with plumose setae. He notices that owing to its extreme fragility it is often met 

 with in a damaged condition. The inner plate of the First Maxillse, he says, is large, 

 broadly oval, apically furnished with two short setae, of which the upper is always plumose, 

 the lower simple, except in Oediceros saginatus, which has both plumose, and in Aceros 

 phyllonyx, which has three setae, all plumose ; in some species of Halimedon he finds only 

 a single simple seta. In the genus (Ediceroides of this Report the number of these setae 

 varies from three to eight. Of the Second Maxillie Schneider says that in most species 

 the two plates are of about equal breadth, in one the outer is the broader, and in two the 

 inner, while the outer is uniformly the longer, and in all genera except Halimedon (to 

 which (Ediceroides may now be added) there is a thicker plumose seta on the middle of 

 the inner margin of the inner plate. 



