TANAIDACEA AND ISOPODA— TATTERSALL. 225 



metamorphosed, and this character is of sufficient importance to constitute, in my 

 opinion, a generic difference between C. darwinii and C. argentinea. 



The second point in the diagnosis of Richardson and Stebbing which requires 

 notice is the structure of the fourth pleopod. Richardson says "both branches of the 

 fourth pai]' of pleopods are similar— fleshy, with transverse folds and without marginal 

 setae " ; and from the figure of the fourth pleopods of C. argentinea we gather that 

 the exopod is without a terminal joint. Stebbing, in his remarks on Euvallentinia 

 darwinii, though not actually in his diagnosis of the genus, states that "the exopod 

 of the fourth pair is clearly two-jointed." I can confirm Stebbing's statement, and 

 venture to think thaj jthis character canjj^e regarded as. of- generic value. 



I am therefore led to remove C. darwinii from the genus Cassidias to which 

 Miss Richardson would refer it, and to uphold the validity of the genus Euvallentinia, 

 Stebbing, a genus of Sphaerominae Eubranchiatae, having both sexes very similar in 

 external aspect, without processes on the thorax ; basal joint of the first antennae not 

 expanded into a free plate nor produced into an acute process ; mouth-parts similar in' 

 both sexes, not metamorphosed in the egg-bearing females ; uropods similar in both 

 sexes, with an exopod which is much shorter than the endopod ; exopods of pleopods 

 three and four two-jointed ; female with marsupial lamellae which overlap in the 

 median line, young developed in internal pouches ; male with an appendix masculina 

 on the second pleopod. 



To this diagnosis may perhaps be added, as Stebbing has done, second thoracic 

 limb of the male prehensile. Whether this character is of generic or specific significance 

 is a matter of opinion, but it is at least interesting in view of Hansen's statement that 

 "in no case has any sexual difference been observed " in the anterior two pairs of 

 thoracic legs among the genera of the Eubranchiate Sphaeromids. 



In only one other genus of Eubranchiate Sphaeromidae, Scutulbidea, Chilton, is 

 the exopod of the fourth pleopods two-jointed, but this genus differs from Euvallentinia 

 in having the exopod of the third pleopod unjointed, and in having the uropods without- 

 exopods. 



32. Euvallentinia darwinii (Cunningham). 



Cymodocea darwinii, Cunningham, 1871, p. 499, pi. LIX, figs. 1-16 ; Studer, 1884, p. 18, 

 pi. II, figs. 6-6&; Beddard, 1886 (2), p. 150; Dollfus, 1891, p. 65, pi. VIII, figs. 8-86; 

 Ortmann, 1911, p. 649. 



Bynamene darwinii, Miers, 1881, p. 79 ; Hansen, 1905 (1), p. 135. 



Cassidias darwinii, Richardson, 1906 (1), p. 22, fig. 27. 



Vallentinia danoinii, Stebbing, 1914, p. 351. 



Euvallentinia darwinii, Stebbing, 1914, p. 944. 



Occurrence. — -Station 38, 52° 23' S., 63° 50' W., 125 fathoms, bottom fauna, three 

 males and three females. 



Remarks. — Two of the males were adult, and measured 13 mm. The third, measuring- 

 only 10 mm., was immature. The females, all adult and two carrying eggs, measure 



2 K 2 



