165 



precedence of those given by Costa, Stimpson and Sp. Bate. The species 

 upon which the "genus was originally founded, is that described below as 

 A. Escliriclitii. Subsequently, the same author described another species as 

 A. Gaimardii, but that species was justly separated by Boeck, as the type 

 of a distinct genus, ]3yUi*. In their general habitus the species of the pre- 

 sent genus exhibit a very uniform appearance, and can, therefore, only by 

 a closer examination, lie distinguished from each other. The most easily 

 recognizable distinguishing marks are afforded by the form of the cephahm 

 and that of the last pair of epimeral plates of metasome, furthermore by the 

 shape of the dorsal carina of the first segment of urosome, the mutual longi- 

 tudinal relation of the antennae, and finally by the structure of the last pair 

 of pereiopoda. The sexual differences are often very pronounced, and make the 

 specific distinction still more difficult, We are acquainted with numerous 

 species of this genus, derived from different tracts of the Oceans, but in the 

 Northern Seas, the genus would seem to be especially abundantly represented. 

 Most of the species are true deep-water forms, and some of them descend to 

 the greatest depths explored. Off the coast of Norway, occur no less than 

 13 species, to be described in the sequel. 



1. Ampelisca typica, Sp. Bate. 



(PL 57). 



letromatus typicus, Sp. Bate, Brit. Assoo. Report 1855, p. 58. 

 Syu : Ampelisea carinata, Bruzelius ? 



Ampelisca (laimardii, Sp Bate (not Kroyer). 



Cephalon about the length of the 3 anterior segments of mesosome 

 combined, gradually tapering distally, and having the tip nearly transversely 

 truncated. Anterior pairs of coxal plates about twice as deep as the corre- 

 sponding segments; 1st pair but little expanded distally; 4th pair more deep 

 than broad, lower edge nearly transversely truncated, and shorter than the 

 hind margin below the posterior angle. Last pair of epimeral plates of 

 metasome right-angled, lateral corners not produced. First segment of uro- 

 some deeply impressed at the base dorsally, especially in the male, and exhi- 

 biting, behind the depression, a rather high carina, terminating in a projecting 

 angle, Corneal lenses distinct, the inferior pair placed close to the lower edge 

 of the cephalon at a short distance from the inferior corners of the front, 

 underlying pigment well defined, red with a chalky-white coating. Superior 

 antennae in female very small, scarcely longer than the cephalon and the 1st 

 segment of mesosome combined, and much shorter than the peduncle of the 

 inferior ones, 1st joint of the peduncle short and thick, 2nd very slender, 



