42 



Gen. 7. LysianaSSa, Milne Edwards, 1R30. 



Body com])ressed, glabrous; with rather tinii integuments and very 

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

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

 longer tluin the superior, in male greatly elongated. Anterior li|i produceil 

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

 nai'row fissure-like incision. Mandibles moi'e elongated than in Ichnopus but 

 otherwise of a rather similar structure, jialp ^•ery slender originating much 

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

 maxilhe with the masticatory lolie not hairy Init armcil at the tip with den- 

 sely crowded strong denticulated spines, basal lol)e rather large, triangular, 

 without distinct apical setae. 2ud 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 guathopoda com]iaratively 

 small, not subcheliforni, propodos tapering, dactylus short am! simple; poste- 

 rior ones alio\it as iu lehnojnis. Pereiojioda rather slender, the 3 posterior 

 jiairs with very broad lamellar basal joints. Branchial lamellfe indistinctly 

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

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

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



Memarls. — This is the genus at first established and inay therefore 

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

 comi)ressed form of the body and the largely developed coxal plates. As 

 distinctive characters may. moreover, he named the structure of the anterior 

 guathopoda 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. Goes as Li/siaiia.'ff-u ri/nibd and likewise by Boeck meiitioned, 

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

 this genus. (-)nly a single species belongs to the Norwegiau fauna ; for the 

 form described by Boeck under the name of Li/t-ianassa phiiiioi<a is unite cer- 

 tainly the adult nuile of L. Cosfre. 



7. Lysianassa Costae. (Milne Edwards). 



(PI. 16, fig. 1.) 

 Li/sidHfissa Costfv, Milne Edwanls, Ann. des Sci. Nat. T. XX, ]\ 3(5.5, PI. 10, fig. 17. 

 Syn: Lt/fiifiuiissii phniiom, Boeck = g. 



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

 r'e))halon eom])aratively narrow, lateral angles consideraldy produced and 



