51 



not very large, masticatory lolio narrow oviil, l)asal one acutely tajiering, 

 pal [I slender, setons. Anterior gnatliojioda of moderate size, sul)clielit'orm ; 

 posterior (mes rather slender, witli the propodos slighth- ])rodnced beneath 

 the minute dactylns. Pereiopoda slender, basal joint of the 3 ])osterior ])airs 

 very large and laminar. Last pair of uropoda small, scarcely reaching beyond 

 the preceding pair; rami not setons nor denticulate, subequal in size, the 

 outer with a distinct spinifoi'm tei'minal joint. Telson siiuaiiiiforni, entire. 



I'cmarls. — This genus is well characterised l)y the peculiar laminar 

 form of the ]ienultimate peduncular joint of the inferior antenna^, liy the 

 digitiform ]ii-ojecting anterior lip, and by the coarse structure of the mandibles. 

 In the form of the telson it agrees with Lifsianassa, hut is otherwise very 

 ditferent. The sexual differences are somewhat analogous to those described 

 aliove in the genus Acidosfonia. the superior autennfe only licing modified in 

 the male, and not, as is usual, the inferior. With that genus it also agrees 

 in the full development of the accessory appendage of the superior antenuBe. 



IJ. Lysianella petalocera, (1. (). Sars. 



(PI. 18, fig. 2). 

 Lysianella petalocera, G. O. Sars, Ovcrsigt af Norges Cnistaceer, I, ]). 7S, PI. 3, fig. 'A. 



Body of female moderately slender, that of male considerably stoiiter, 

 the mesosome being miich sliorter in pro])ortion to the metasome. Cephalon in 

 female about the length of the first segment of the mesosome, with the lateral 

 corners somewhat ]n'ojecting and subangular, in male much deeper and having 

 the lateral corners less projecting. Tlie 4 anterior pairs of coxal plates about 

 twice as deep as the bod\'; 4tli pair distinctly emai'ginated postei'iorly with 

 the inferior pai't considerably dilated; iltli ])air scarcely deeper than they are 

 liroad. Last pair of epimeral plates of metasome rather lai'ge and obtusely' 

 rounded at the posterior corner. Eyes oval, dark purplish brown, with a 

 reddish coating; in nmle consideralilj' larger tlian in female. Su])erior antenna? 

 in female about the length of the cephalon and tlie 2 first segments of tlie 

 mesosome crnnbiued ; peduncle not vei'y strong, first joint about twice tlie 

 lengtli of the other two combined; flagellum rather slender, 8-articulate, 1st 

 joint about the length of the 2 succeeding ones combined; accessory appendage 

 a little shorter than the fiagelluin, Imt scarcely more slender, 4-articulate. 

 Su])erior antenna' in male niucli stronger, the peduncle l)eing considerably 

 tumeficated and the 1st joint of the thigellum very large and densely clotlied 

 witli long sensitive hairs. Liferior antenna; with the peunltimate joint of the 

 peduncle rounded oval, anterifir edge strongly curved, flagellum S-articulate. 

 Anterior gnathopoda with tlie propodos rather narrow, about the length of 



