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



brancliial vesicles scarcely reaching beyond the hind lobe of the side-plate. The first 

 joint expanded, of nearly even -n-idth throughout, but with convex margins, the front 

 fringed with eight small spines, the hinder serrate, carrying cilia ; the short second joint 

 has two spines on the front margin ; the third has five on the straight front margin, 

 three or four on the hind margin, and a group at its very decurrent apex. 



Fourth Perxopods similar to the third, but rather larger. 



Fifth Perwopods. — The first joint broader than the preceding, and behind much 

 longer, the hind margin rising above and descending below the front ; both margins very 

 convex ; the second and third joints similar to those of the fourth perseopods. 



Pleopods. — The coupling spines very short, with two strong, lateral, retroverted teeth 

 besides that at the apex ; on the peduncle of the third pair there was observed an apical 

 spine ; the inner ramus carries apparently only one cleft spine ; the joints of the inner 

 ramus seven in number, of the outer eight. 



Uropods. — Peduncles of the second pair as long as the inner ramus, reaching as far 

 as or a little beyond the apex of thetelson ; the inner ramus much longer than the outer, 

 slender, with three or four spines on either margin, and ending in a sharp nail ; the 

 outer ramus more than half the length of the inner, with three spines on the inner margin, 

 not ending in a nail but very acute. The other pairs missing. 



Telso7i not twice as long as broad, the sides a little curved, converging to a pointed 

 apex. 



Length. — The specimen, in the position figured, measured, from the top of the head 

 facing forwards to the top of the third segment of the pleon facing backwards, scarcely 

 one-tenth of an inch , a size which may suggest an excuse for the imperfect account of the 

 mouth-organs. 



Locality. — Station 145, ofi" Marion Island, December 27, 1873; depth, 100 fathoms; 

 bottom, volcanic sand. One specimen ; a female, with eggs. 



Remarks. — The specific name refers to the place of capture. A specimen of Amphi- 

 lochus from the Clyde, kindly sent to me by Mr. David Eobertson, agrees in most respects 

 with Boeck's description of his Amphilochus tenuimanus, and has also a great resemblance 

 to the present species ; the maxillipeds in the Scotch form and in that from the Southern 

 Ocean are remarkably alike, but in the smaller Challenger species the outer plates of 

 these organs are distally broader, and though having the same armature have it differently 

 arranged ; the third joint of the mandibular palp is much longer than the second, instead 

 of about equal to it ; the finger in each pair of gnathopods is prolonged beyond the palm, 

 and is very diS"erent from that of the larger species ; there appear also to be diff"erences 

 in the shape of the side-plates, and altogether the sum of the diff"ereuces, added to the 

 great distance between the localities at which the specimens occur, makes it unsafe to 

 place the northern and southern examples in one and the same species. 



