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



Third Perieopods. — Side-plates broader tliau deep. First joint rounded, not so 

 large as the side-plate, a spine and seta at the lower end of the front margin, a minute 

 cilium high up on the hinder ; the second joint with a seta followed by a spine on the 

 lower part of the front margin, and some microscopic pectination between ; the third 

 joint broadly expanded, decurrent behind the fourth joint, with two spines on each 

 border ; the rest of the limb similar to that of the preceding j^air. 



Fourth Pevieojjods. — Side-plates with the convex hinder margin considerably longer 

 than the straight front one. The first joint much larger than the side-plate. All the 

 joints constructed as in the preceding pair, but somewhat larger, especially the first and 

 third. 



Fifth Pera?opo(^s. ^Side-plates smaller than those of the preceding segment, hind 

 margin not much longer than the front one. First joint a little larger than that of the 

 preceding pair, the cilium of the hind margin lower down ; third and following joints 

 smaller than those of the adjoining pair. 



Pleopods. — Peduncular spines two, perhaps more, the rami with four or five 

 joints. 



Uropods. — Peduncles of the first pair as long as the longer ramus, the rami short, 

 pointed, the longer with one spine near the centre of its margin, the edges finely 

 pectinate, the shorter ramus seemingly with smooth edges ; the second pair smaller 

 than the first, the peduncle about equal in length to the longer ramus, which has 

 pectinate edges but no spine, the shorter ramus has a cilium near the base ; no rami were 

 discerned on the third pair. 



The Telson appears to be short and broad with a small cleft or terminal emargination, 

 having each apex capped by two spines, the outer one the larger, each carrying an 

 accessory thread. 



Length. — The specimen in the position figured measured rather over a tenth of an 

 inch. 



Locality. — Station 313, off Cape Virgins, Patagonia, January 20, 1876 ; lat. 52° 20' S., 

 long. 67° 39' W.; depth, 55 fathoms ; bottom, sand. One specimen. Trawled. 



Remarks. — The specific name refers to the place of captiu-e, at the entrance to the 

 Strait of Magellan. 



Acontiostoma 2^epinii, n. sp. (PL XXXIL). 



A little, compact, hauy species ; back of perseon well-rounded and broad, afterpart of 

 pleon pinched in ; the head almost covered by, though jiartially visible through, the 

 semitransparent first perceon-segment and its side-plate; the fourth to the seventh perseon- 

 segments deep ; the third pleon-segment dorsally rounded, distally rising above the 



