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



the apical margin, the outer of the two being the longer and thinner; the first joint of 

 the palp substantial, nearly as long as the second, the fourth joint slender, with a small 

 nail ; a dorsal cilium near the nail, and a row of four cilia near it on the inner surface. 



First Gnathopods. — Side-plates widened below but not much outdrawn in front ; 

 first joint of great thickness, exceeding in length the third, fourth and fifth united ; the 

 second, third and fourth subequal in length ; the second with several setse along its hind 

 border, the third with no free front border, the hind border furred, carrying a group of 

 spines near the apex ; the small free hind margin of the triangular cup-like wrist furred ; 

 the hand oblong, but a good deal broader at the base than at the palm ; both hand and 

 finger very similar in the details to those of Orchomene musculosus. 



Second Gnathopods. — These difi'er from those of Orchoviene musculosus in that the 

 wrist is not longer than the second joint, and, instead of being most expanded close to 

 the apex, is here most expanded midway between the third and fifth joint, so as to have 

 a plump instead of an elongate appearance ; the hand is also less elongate, and the little 

 palm is deeply excavate, the process which bounds it being squared and pectinate 

 apically, carrying a pectinate spine ; the inner end of the finger appears to be armed wdth 

 a brush of microscopic cilia or denticles, and when this antagonizes with the hinder 

 process of the palm there is a clear space left between the palm and inner margin of the 

 finger. The marsupial plate is narrow, with very long setse. 



First Perwopods. — The oblong side-plates are of even width throughout. The 

 branchial vesicles are very long and very broad except at the neck, wdthout folds. The 

 joints of the limb similar to those in OrchoTnene musculosus, with which in general 

 the other limbs also agree. 



Third Perseop)ods.- — The side-plates rather less elongated behind. 



Fourth Pe7-ieopods. — The branchial vesicle behind the neck presents two lobes, one 

 ascending the other descending, below and in front of which the main part of the vesicle 

 consists of a large circular expansion, against which lies a narrow accessory sac of about 

 equal length, curved at the tip. 



Fifth PersBopod. — The branchial vesicle is here a simple sac which rises a little 

 above and descends a great way below its point of attachment ; the outline is convex in 

 front, concave behind, the straight upper margin running obliquely downwards to form 

 a small but conspicuous backw^ard-directed process. The first joint of the limb is extremely 

 expanded behind and only very slightly narrowed below. 



Pleopods of the third pair with four cleft spines on the first joint of the inner ramus, 

 those of the second pair with five. 



Uropods. — Peduncles of the first pair considerably longer than the rami ; rami 

 slender, with few spines, a series of five on one edge of the outer, of four on one edge of 

 the shorter inner ramus ; edges of the rami microscopically pectinate ; peduncles of the 

 second pair longer than the rami, which are equal in length to one another ; peduncles of 



