30 



[No. 7. 



jecting within the incubatory cavity, the 3 anterior of which 

 are of considerable size. They exhibit a glandular structure 

 and may perhaps serve to secrete some nourishing matter to 

 be absorbed by the embryos during the last period of their de- 

 velopment 



Eespecting the inner organs, the alimentary tube can be at 

 once discerned through the pellucid body by its yellowish colour. 

 It is quite simple, without any loops or circumvolutions. The 

 anterior part, contained within the head, is considerably dilated 

 and curves downwards, but without any trace of coecal appen- 

 dages. Also the posterior part is sharply curved before entering 

 the tail; the muscular rectum is rather short and opens at the 

 tip of the tail behind the caudal claws. 



The heart is rather small, of a rounded oval form and, as 

 usual, provided with a single venous fissure on each side. Just 

 above it, and somewhat in front, is seen a small cup-shaped or- 

 gan, located immediately within the dorsal edge; it would seem 

 to represent the so-called affixing organ in other (Tadocera. 



The ovaries are often very large and conspicuous — by 

 reason of their dark greenish colour (see fig. 1), covering at the 

 sides a considerable part of the intestinal tube. 



The summer-eggs, when recently discharged into the incu- 

 batory cavity, are oval in form and exhibit in the centre a dark 

 greenish cellular vitelline substance. They are often rather nu- 

 merous, from 10 to 15, distending therefore the dorsal part of 

 the carapace (see fig. 2). Of winter-eggs on the other hand, more 

 than one in each individual (see fig. 3) has never been found; it lies 

 exactly in the middle of the incubatory cavity with its greater 

 diameter parallel to the axis of the shell. As with the forms 

 belonging to the familly Daphnidae (proper), this ovum becomes 

 enveloped with a true ephippium of an oval pyriform shape, 

 and sharply defined from the carapace by its very distinct and 

 coarse reticulate sculpture (see fig. 3). The egg itself is some- 

 what larger than the summer-eggs, and contains a finely gra- 

 nular opaque substance of a dark brownish colour. 



The adult male (fig. 6) is much smaller than the female an 



