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than wide and arcuate above, its outer margins are slightly concave and it narrows distinctly 

 towards the tip; the anterior tubercle is more conical, though obtuse and shorter than the 

 other. The two anterior prominences are thickly covered with microscopical tubercles each of 

 which ends in two small teeth ; similar microscopical tubercles also cover the adjacent submedian 

 lobes of the distal border, they here gradually become smaller. Between the anterior and the 

 posterior tubercles the upper surface of the petasma carries at either side a small, compressed, 

 narrow tooth or lobule, with rounded tip and curved forward. 



Though the female is much mutilated, the thelycum appears as a horizontal plate between 

 the three posterior pairs of legs; the anterior margin is rounded, like also the less wide posterior 

 and the thelycum shows its greatest width between the legs of the 4"^ pair-, the upstanding, 

 antero-lateral margins are thickened, the upper surface appearing anteriorly concave. 



Remarks. Genn. Pasithea is closely related to Ainalopenaetis elegans S. I. Smith. 

 Apart from the generic character — the presence of podobranchs on the three anterior pairs 

 of pereiopods — it is the petasma that has a different form, as also the thelycum ; the 2°'^ 

 antennular article appears in the atlantic species a little shorter and the propodus of the 

 4''^ and ^^^ legs appears slightly longer, according to Bouvier, than the carpus. Probably there 

 are still more differences. 



Gennadas Calmani Kemp from Japan is also closely related. In this species, however, the 

 cervical and the post-cervical groove are somewhat farther distant from one another and both 

 are feeble dorsally, not interrupting the post-rostral carina. The antennal scale has a somewhat 

 different form, the carpus of the 3"^ pair is four-fifths the length of the merus, while in Genn. 

 Pasithea it is comparatively longer, petasma and thelycum, finally, are also differently shaped. 



Except the i^' pair of legs, nothing is known about the pereiopods of Genn. borealis 

 Rathb. ; the chela of the i^' pair seems to be shorter than the carpus (R.\thbun, Decapod 

 Crustaceans Northwest Coast of Xorth America, 1904, p. 148, Fig. 89^), whereas in Genn. 

 Pasithea it is longer than it. Thelycum and petasma are apparently also different. 



73. Gennadas clavicarptts de Man. 



J. G. DE Man, Notes from the Leyden Museum, Vol. XXIX, 1907, p. 144. 



Stat. 128. July 22. 4°27'N., I25°25'.7E. Celebes Sea. From /oom. to surface. i adult female. 

 Stat. 141. August 5. i°o'.4S., I27°25'.3E. near Batjan. From 1500 m. to surface. i very 



young female. 

 Stat. 230. November 14. 3°58'S., 128° 20' E. Banda Sea. From a depth of 2000 m. to surface. 



5 males and 5 females of different size. 



This species also belongs to the genus Gennadas^ the three anterior legs being provided 

 with a podobranch ; the podobranchs are, in this species, not an outgrowth from the base of 

 the epipod, but are inserted close to the latter. 



The adult female from Stat. 128 will be first described. Carapace, rostrum included, 

 9 mm. long, the abdomen 25 mm., total length 34 mm. Looked at from above, the carapace 

 shows its greatest width just in the middle, being here 5 mm. wide and it narrows a little more 

 anteriorly than posteriorlyi the carapace presents its greatest height of 5,6 mm. just behind 



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