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



First Perseo2wds. — Side-plates a little broader and longer than those of the preceding 

 pair ; branchial vesicle from a small neck swelling out into a broad sac with a narrow 

 terminal lobe ; first joint of the leg with the front margin straight ; third joint stouter 

 and much longer than the fourth, but little produced downwards ; fourth joint stouter 

 than fifth, subequal to it in length ; fifth joint naked, like the two preceding, on the 

 forward margin except at the apex ; on the hinder margin all three have groups of spini- 

 form seta3, one long one at the apex of the fourth joint and some shorter ones on the 

 border of the fifth seeming to be truly spines ; the finger long, narrow, slightly curved, 

 with edges bare except for the feathered cilium on its back near the base. 



Second PerseoiMds. — Side-plates broad below, excavated above ; the marsupial plates 

 in this and in the preceding segment long and very narrow (in the specimen figured) ; the 

 joints of the leg like those of the preceding pair. 



Third Perseopods. — The branchial vesicle broad and squared above, curling round in 

 a narrow lobe below, with a long thin accessory vesicle starting from the base. First 

 joint very broad, slightly broader above than below, lower margin behind with a deep 

 rounded lobe overlapping the next joint, the lateral margins very little curved ;"the third 

 joint short, broad, somewhat decurrent behind, with spines on the hinder margin, spines 

 and fine setse on the front margin ; fourth joint ovate, somewhat shorter and much 

 narrower than the preceding, garnished in like manner ; fifth joint slender, longer 

 than the fourth, with few spines ; finger long, thin, little curved, seemingly quite 

 naked. 



Fourth and Fifth Perseopods similar in general structure to the third, but with the 

 first joints longer and about the same breadth, the third joint in the fifth pair less dilated, 

 the fifth joint longer in proportion to the finger. As the dorsal cilium of the finger is 

 here present, it may be only accidentally missing from the third pair. Branchial vesicle 

 of the fourth pair was on one side of the specimen not unlike the accessory vesicle of the 

 third, but curved instead of straight, and at the top broader, as also in the somewhat 

 narrowed middle part, while the terminal part is thinner; on the other side the lower part 

 of the branchia was expanded. The branchial vesicle of the fifth pair is quite small, 

 irregularly shaped both as regards the neck lobe and the larger terminal one, which has 

 the appearance of being attached to the other by one corner. 



Pleopods. — In the coupling spines the apex is rounded, undilated ; the lateral retro- 

 verted teeth are two in number ; on the large basal joint of the inner ramus there 

 are three cleft spines of the usual form, as described in the account of Cyphocaris 

 micronyx (p. 660) ; the joints of the rami are from sixteen to twenty in number, the outer 

 ramus apparently as a rule having one or two more joints than the inner. 



Urop>ods. — The first pair have the peduncles somewhat longer than the rami ; the 

 outer ramus rather longer than the inner ; both stiliform, slightly curved at the tips ; in 

 the second pair the peduncle is rather shorter than the rami ; these are subequal, each, as 



