42 



Gen. 7. LyslanaSSa, Milne Edwards, 1830. 



Body compressed, glabrous; with rather firm integuments and very 

 large coxal plates. Superior antennae having the 2 outer joints of the peduncle 

 more elongated than in most other forms; inferior ones in female scarcely 

 longer than the superior, in male greatly elongated. Anterior lip produced 

 anteriorly to a large linguiform plate defined from the epistome by a very 

 narrow fissure-like incision. Mandibles more elongated than in Ichnopus but 

 otherwise of a rather similar structure, palp very slender originating much 

 nearer the base than does the very small molar expansion. First pair of 

 maxillae with the masticatory lobe not hairy but armed at the tip with den- 

 sely crowded strong denticulated spines, basal lobe rather large, triangular, 

 without distinct apical seta?. 2nd pair with the inner lobe much broader than 

 the outer. Maxillipeds well developed, masticatory lobes of moderate size, 

 regularly oval, palp slender and elongated. Anterior gnathopoda comparatively 

 small, not subcheliform, propodos tapering, dactylus short and simple; poste- 

 rior ones about as in Ichnopus. Pereiopoda rather slender, the 3 posterior 

 pairs with very broad lamellar basal joints. Branchial lamella? indistinctly 

 folded transversely on the one face. Uropoda slender, successively dimin- 

 ishing in size posteriorly, last pair with the rami narrow lanceolate, naked 

 in female, densely setiferous in male. Telson small, squamiform, entire. 



Remarks. - This is the genus at first established and may therefore 

 be regarded as the type of the family. It is easily known by the slender 

 compressed form of the body and the largely developed coxal plates. As 

 distinctive characters may, moreover, be named the structure of the anterior 

 gnathopoda and especially that of the telson. The genus would seem to have 

 an evident southern range and to comprise several species, some of which 

 however, may still be regarded as rather doubtful. Thus the arctic form 

 described by Dr. Groes as Lysianassa cyntlta and likewise by Boeck mentioned, 

 though with some doubt, as a Lysianassa, can certainly not be adduced to 

 this genus. Only a single species belongs to the Norwegian fauna; for the 

 form described by Boeck under the name of Lysianassa plnmosa is quite cer- 

 tainly the adult male of L. Costa. 



7. Lysianassa Costae, (Milne Edwards). 

 (PI. is, fig- i.) 



Costce, Milne Edwards, Ann. des Sci. Nat. T. XX, p. 365, PI. 10, fig. 17. 

 Syn : Lysianassa irtnmosa, Boeck = g . 



Body rather slender and compressed, with the back narrowly rounded. 

 Cephalon comparatively narrow, lateral angles considerably produced and 



