1052 THE VOYAGE OF H.M.S. CHALLENGER. 



and a setule ; the cleft is nearly four-fifths of the total length of the telson, the surface 

 has on each side a couple of slender spines near the top, and low down two stouter ones. 



Length. — The specimen, in the position figured, measured, in a straight line from the 

 front of the head to the apex of the third uropods, thirteen-twentieths of an inch. 



Locality.— Station 24, off Culebra Island, St. Thomas, March 25, 1873 ; lat. 18° 38' 30' 

 N., long. 65° 5' 30" W. ; depth, 390 fathoms; bottom, Pteropod ooze. One specimen, 

 female. 



Remarks. — The specific name refers to the considerable depth from which the species 

 was obtained. 



The present species bears a great external resemblance to Ampelisca odontoplax, G. 

 0. Sars, taken in the Norwegian North Atlantic Expedition, " off the coast of Helgeland 

 (Station 147) at a depth of 142 fathoms" ; the station referred to being in lat. 66° 49' 

 N., long. 12° 8' E. ; but in that species the two pairs of gnathopods are described 

 as " very slender, with the hand very small and narrow," and the first joint of the fifth 

 perajopods is said to be at the extremity " almost vertically truncate," this expression 

 referring to the lower margin behind, which in the Challenger species is very much 

 rounded. In Sars' figure the fifth and sixth pleon-segments are drawn as distinct, not 

 coalesced, but the circumstance is not referred to in the text. According to Buchbolz, 

 Die zweite deutsche Nordpolarfahrt, 1874, p. 357, these segments are distinct in 

 Ampelisca eschrichtii, Krdyer. 



Ampelisca fusca, n. sp. (PI. CV.). 



Head sharply compressed on the dorsal line, in front emarginate at the top ; from 

 the lower angle of the emargination the sides slope backwards with a slightly sinuous 

 outline ; the back is rounded as far as the third pleon-segment, which with the fourth is 

 slightly keeled ; the fourth segment has a transverse dorsal depression, a setule on the 

 back, the dorsal apex slightly projecting ; the coalescent fifth and sixth segments are 

 scarcely distinguished dorsally except by a slight transverse depression ; the sixth segment 

 carries a pair of dorsal setules, and the hinder angles on either side of the medio-dorsal 

 line are slightly incurved ; the lower hinder angles are as usual outdrawn ; the postero- 

 lateral angles of the first three pleon-segments are rounded. 



Of the round simple Eyes one pair seem to project slightly beyond the margin of the 

 head just below the lateral angles, while the other pair are a little above tliese angles, 

 within the emarginate front border of the head. 



Upper Antennae rather longer than the lower. First joint rather short and thick, 

 carrying several feathered cilia ; the second joint much longer than the first, longer than 

 the head, with slender spines, some very long, on the under margin and on the surface. ; 



