1909.] CRUSTACEA OF THE GENUS GENNADAS. 727 



merus of the second maxillipecle (PI. LXXIV. fig. 4) is not quite 

 twice as long as wide ; the anterior prominence is almost one -third 

 the total length of the joint. 



In the first pair of pereiopods the carpus, which is slightly 

 shorter than the chela, is three-fifths the length of the merus. 

 In the second pair the dactylus is equal in length to the palm, 

 the whole chela b6ing a little shorter than the carpus. The 

 merus of the third pair is very distinctly shorter than the carpus, 

 the chela is rather more than half the length of the carpus, and 

 the dactylus is almost as long as the palm. 



The sternum of the first abdominal somite bears a large and 

 stout median spine ; on the succeeding somites this is reduced to 

 a blunt tubercle. The sixth somite alone is dorsally carinate. 

 The telson is squarely truncate apically and is furnished with five 

 plumose setfe between the usual pair of stout lateral spines. 



The three females differ slightly in regard to the thelycum. 

 One example (PL LXXY. fig. 6) shows the dark yellow and toughly 

 chitinized spermatophoi-es partially inserted beneath the large 

 rounded plate, lying between the third and fourth pairs of legs. 

 A second specimen is as nearly as possible identical with this, 

 but the spermatophores are wholly covered by the thelycal plate. 

 In the third example, which shows no spermatophores, the pos- 

 tei'ior plate is much shorter than the other two (PI. LXXY. fig. 7), 

 but it is possible that this is due, at least in part, to the contracted 

 condition of the specimen. 



Attempts to remove the spermatophores proved unsuccessful, 

 for their inner ends are very firmly fixed (probably cemented) in 

 a pocket or spermatheca lying beneath the plate. 



Gennadas bouvieri differs from all the other species in the 

 ' Challenger ' collection in the proportional lengths of the merus 

 and carpus of the third pair of pereiopods. It takes rank in the 

 second section of Bouvier's synoptic table, along with Gennadas 

 talismani, G. tinayrei^ and G. valens. We have no precise in- 

 formation concerning the branchial formulse of these three species, 

 but from Smith's account * it seems probable that valens is a true 

 Amalopenceus . 



Gennadas scutatus Bouvier. (Plate LXXY. fig. 2.) 

 Gennadas scutatus, Bouvier, Bull. Mus. Oceanog. Monaco, no. 80, 



1906, figs. 8 & 13, and Res. Camp. Sci. Monaco, xxxiii. 1908, 



p. 42, pi. viii. 



St. 267. N. Pacific. 9° 28' N., 150° 49' W. 2700 fathoms. 

 One male, 21 mm. 

 The ultimate joint of the mandibular palp is only a trifle 

 shoi-ter than the width of the basal joint. The third joint of the 

 endopod of the second maxillipede is wider than in Bouvier's 

 figure, and the fourth joint is much less prominent. With the 



* Rep. U. S. Fish Comm. for 1882 (1883), p. 402. 



