TUBICOLOUS AMPHIPOD — CHILTON. 6 



In large sized males the lower antennse are stouter and more 

 pediform than in younger specimens, and the long setse are by no 

 means so conspicuous. 



The mouth parts appear to correspond closely with Stebbing's 

 description, but I have not examined them in great detail. 



The first gnathopoda are the same in both sexes and agree with 

 Stebbing's description as closely as can be expected when allowance 

 is made for individual variation. 



The second gnathopoda differ very much in the two sexes. In 

 the female they do not differ very greatly from the first gnathopoda 

 and agree very closely with the description already given by Mr. 

 Stebbing. I give a drawing for the sake of comparison with the 

 second gnathopoda of the male, (see fig. gn. 2 ? ). In the male the 

 second gnathopoda differ considerably from those of the female 

 and also differ very much at difterent stages in the development of 

 the same individual. The form most commonly met with is that 

 shown in fig. gn. 2 ^ B, which represents the second gnathopod 

 of a moderate sized male; it will be convenient to describe this first. 



The first free joint, the hasos, is narrow at the base where it 

 articulates with the moderate sized side-plate but rapidly widens 

 until at the widest part it is more than half as broad as long ; the 

 anterior edge is straight except near the base and is fringed with 

 about ten spinules, the posterior margin is strongly convex and 

 bears two or three setas at the apex ; the ischios and the meros 

 are of the usual shape and not unlike those of the female ; the 

 meros has the distal extremity produced, rounded and tipped with 

 a few setpe ; the carpus is very large and broad, its anterior mar- 

 gin very convex especially towards the base, a small group of sette* 

 at its distal extremity, the posterior margin is indistinctly serrate 

 and bears five groups of long setse in the serrations, other shorter 

 setfe are situated between the serrations and a few on the surface 

 of the joint ; the postero-distal corner is pi'oduced acutely and 

 reaches about half way along the inner mar-gin of the propodos, 

 and between this corner and the inner articulation of the propodos 

 is a short rounded lobe reaching only about half as far. The 

 propodos is considerably shorter than the carpus, rather more than 

 twice as long as broad, the anterior margin curved and bearing 

 about six spinules, that at the apex the longest ; the posterior 

 margin with the basal half smooth, but the distal half minutely 

 serrate or more strictly speaking crenate, the whole margin fringed 

 with abundant long setse, a few others being situated along the 

 surface of the joint ; the dactylos is like that of the female and 

 has the inner margin denticulate towards the distal end, but the 

 inner margin of the terminal tooth again is smooth. 



* These serrations are not shown very distinctly in the plate. 



