1 895- No. 8. SOUTH-AFRICAN ENTOMOSTRACA. 4/ 



Colour more or less bluish, in the male generali}' with an orange tinge. 

 Length of adult female 3,00 mm., of male 3,70 mm. 



Remarks. This is the only as yet known species of the genus. Its 

 specific name refers to the peculiar development of the caudal rami in 

 the female. 



Description of the female. 



The length of adult specimens measures about 3 nmi., and this lorm, 

 accordingly grows to a rather large size as compared with other fresh- 

 water Copepoda. 



The form of the boch* (see PI. 7, figs, i & 2) is comparatively robust, 

 with the 2 chief divisions sharply marked of from each other. The ante- 

 rior division, comprising the cephalosome and metasome, is of ol)long oval 

 form, with the dorsal face evenly vaulted, and the greatest width some- 

 what in front of the middle. It is divided into 6 distinctly defined seg- 

 ments, the ist of which, representing the cephalosome, is much the lar- 

 gest, though not attaining the length of the 3 succeeding ones combined. 

 Seen dorsally (fig. 2), this segment is evenly rounded in front. In a 

 lateral view (fig i), it appears somewhat blunted anteriorly, and terminates, 

 inferiorlv, just in front of the insertion of the anterior antennae, in a small, 

 deflexed rostral projection, which does not exhibit any tentacular appen- 

 dages. The last segment of the metasome is deeply emarginated in the 

 middle, and projects on each side to a rather large, posteriorly pointing 

 lamella of triangular shape. This lamella is quite entire, not, as in most 

 species of the genus Diaptomus as Avell as of Boeckella, divided into 2 lobes. 



The posterior division of the body, the urosome or tail, is much 

 narrower than the anterior, and very movably connected with the same. 

 Including the caudal rami, it scarcely exceeds half the length of the ante- 

 rior division. In structure it differs considerabh" from that in most other 

 Copepoda, being composed of onh^ 3 segments, besides the caudal rami 

 (see fig. 3). The ist, or genital segment is considerably expanded in 

 its proximal part, forming, on each side, an angular projection, and, below, 

 a rounded prominence containing the genital orifice. The 2nd segment is 

 shorter than the ist, but gradually widens distally, with the outer part 

 rather broad and flattened. At its end, dorsally, the anal orifice occurs 

 in the form of a longitudinal fissure, parth* obtected, in front, by a 

 projecting curved edge. 



The caudal rami (ibid) exhibit a rather peculiar appearance, being 

 ver\' large and lamelliform, whereas the marginal setae are unusually short. 

 The rami considerably exceed, in length, half the remaining part of the 



