^O G. O. SAKS. M.-N. Kl. 



& 2). Especially are the ovaria very conspicuous by their dark greenish 

 colour. The alimentary tube is best seen in a lateral view of the animal 

 (fig. i), and, as usual, is rather wide in its anterior part, where it is filled 

 with a light yellowish substance, becoming gradually narrower posteriorly. 

 The heart is also very conspicuous in the living animal by its rapid pul- 

 sations, occurring, as usual, dorsally, at the limit between the 2 first seg- 

 ments of the metasome. 



The colour is, generally, a light yellowish green, more or less tinged 

 with indigo blue, especially on the sides, and along the posterior edges of 

 the seo"ments. A narrow, somewhat arcuate band of the same colour, may 

 often also be found to extend across the anterior part of the cephalosome, 

 giving it the appearance of being divided into 2 segments, which, how- 

 ever, in reality, do not exist. The genital protuberance of the ist seg- 

 ment of the tail is tinged with brownish orange, and the caudal lamellae 

 are generally deep blue at the tips. 



The adult male (PI. 7, fig. 5) is somewhat smaller than the female, 

 scarcely exceeding in length 2,70 mm., and, as usual, exhibits a more 

 slender form of the body. It is, moreover, distinguished by the last seg- 

 ment of the metasome wanting the lamellar projections present in the 

 female, and by the rather different appearance of the tail. The latter 

 (fig. 6) is much more elongated and slender, about equalling in length 2/3 

 of the anterior division. It is divided into 5 well-defined segments, the 

 ist of which is somewhat thicker, but scarcely longer than the others, 

 which are almost alike. 



The caudal rami (see fig. 6) difter considerably in their appearance 

 from those in the female, being much narrower, and very slighdy expanded 

 distally. They are, moreover, somewhat assymetrical, the left ramu.s 

 being larger than the right, which is turned obliquely outwards. The 

 marginal setae are comparatively more elongated, and do not exhibit any 

 distinct bulbous dilatation at the base. The seta of the exterior edge is, 

 on the right ramus, much coarser than on the left, almost spiniform, and 

 only ciliated on one of the edges. The ledge to which this seta is 

 secured, appears, also, much more strongly marked than on the left side. 



The anterior antennae, as in other male Diaptomidae, are unequally 

 developed, the right antenna (see PI. 7, fig 5, PI. 8, fig. 10) being modi- 

 fied to a strong grasping organ, by the aid of which the male gets hold 

 of the female during copulation. While the left antennae exhibits the 

 normal number of articulations, the right one is only composed of 23 

 joints, some of the joints being, apparently, fused together. The 4 outer 

 joints (see PI. 8, fig. 10) form together a very movable terminal part, 



