178 G. STEWARDSON BRADY. 



Apart from the structure of the shell, to which oue need 

 not perhaps attach very great importance, the principal dis- 

 tinctive characters of this genus, as described by Sars, are 

 " parthenogenetical " reproduction, the unequal and pecti- 

 nated claws of the caudal rami, and the rather abnormal 

 build of the first maxillar palps. G. W. Miiller, however, 

 adds to these characters the asymmetrical structure of the 

 two caudal rami, though this want of symmetry is not found 

 in the types previously described — S. malcolmsoni and S. 

 chevreuxii. A still more important divergence is the 

 bisexual character of S. sinuata as described by Miiller. 

 In this species the two sexes are fully developed, so that the 

 " exclusively parthenogenetical " character ascribed to the 

 genus by Sars cannot here apply. But no males have been 

 found in the case of S. aldabraB, and in this species Miiller 

 states that the recep taenia seminis are always empty. 

 This accords Avith my own observation. Still, I find it difli- 

 cult to believe that these organs should exist, as they do in 

 many true Oypridee, apart from any possible functional use, 

 and it seems to me not unlikely that some day or other males 

 may be found in species which we are at present constrained 

 to call " parthenogenetical." The present generic allocation 

 of the various species must be looked upon as provisional. 



Stenocypris aldabrae G. W. Miiller. PI. XXXI, figs. 1-6. 



Stenocypris aldabras Miiller, loc. cit., p. 275, PI. YII, 



figs. 1-8. 



Shell seen laterally elongated, siliquose, highest in the 

 middle, height equal to less than half the length ; anterior 

 extremity well rounded, posterior sloping* steeply and almost 

 in a right line to the ventral angle, which is rounded ofl: ; 

 dorsal margin evenly arched, rather flattened, ventral sinuated 

 in the middle, otherwise straight (fig. 1) ; seen dorsally the 

 outline is much compressed, elongated, fully four times as 

 long as broad, with acutely pointed extremities (fig. 2). 

 Surface of the shell quite smooth ; colour, grey. Length, 



