1036 THE VOYAGE OF H.M.S. CHALLENGER. 



1882. Ampelisca, Haswell, Catal. Australian Crust, p. 234. 



1882. ,, Sars, Oversigt af Norges Crustaceer, pp. 29, 107. 



1884. ,, Schneider, Crust, og Pycn. Kvasnangsfjorden, p. 120. 



1885. ,, Cams, Prodromus Fauna; Mediterranean, p. 408. 



1885. ,, Sars, Den norske Nordhavs-Exp., p. 196. 



1886. ,, Gerstaecker, Bronn's Klassen und Ordnungen, Bd. v. Abth. ii. p. 505. 



1887. ,, Chevreux, Catal. Crust. Aniph. Bretagne, p. 21. 



For the original definition of the genus, see Note on Kroyer, 1842 (p. 199); for the 

 definition of Araneops, see Note on Costa, 1857 (p. 296); for that of Pseudopthalmus, 

 see Note on Stimpson, 1854 (p. 279) ; and for that of Tetromatus, see Note on Spence 

 Bate, 1857 (p. 293). Boeck in 1876 gives the following definition to Ampelisca : — 



" Mandibles with the second joint of the palp broad ; the third joint much narrower, 

 but almost of the same length as the second. 



" Maxillipeds with the third joint of the palp apically much dilated. 



"Eyes four, placed on the anterior margin of the head. 



"Lower Antennie. with the first and second joints of the peduncle not externally 

 visible. 



" Fifth Perieopods with the first joint triangular, elongate behind and below ; the 

 fifth joint elongate, oval, longer than the fourth ; the finger lanceolate. 



" Tliird Urop>ods extended beyond the extremity of the First and Second pairs, 

 the rami elongate, laminar, furnished with long plumose setae. 



" Telson elongate, more than twice as long as broad, cleft to the base." 



The Challenger species do not show the palp of the mandibles in all cases with its 

 second joint broad, or with its third joint 1 almost of the same length as the second, and 

 in one species, Ampelisca abyssicola, the fifth joint of the fifth perseopods is shorter, 

 instead of longer, than the fourth. 



Spence Bate, in his definition of Ampelisca in 1878, includes the character "eyes 

 imperfect," but though the eyes in the Ampeliscidae are very differently constituted from 

 those of other Amphipoda, it is doubtful whether they should be considered imperfect : 

 behind each of the four bright lenses in the head of an Ampelisca there is a circlet of 

 very numerous optical elements (indicated in fig. a.i. PI. CIIL), which are by no means 

 suggestive of imperfect vision. 



Ampelisca acinaces, n. sp. (Pis. CI., CII.). 



The animal acutely compressed all along the dorsal line, the head elongate, in front 

 narrow and rather sinuously truncate ; the postero-lateral angles of the first two pleon- 

 segments rounded, the third segment having the lower margin nearly straight and making 

 almost a right angle with the hind margin ; the fourth segment of the pleon having a 



Boeck himself finds this third joint only half as long as the second in Ampelisca eschrichti. 



