Daphiiia schsefleri. 



Fig. 



1. Post abdomen of female. 



2. Post-abdomen of male. 



3. Male antennule. 



4. Brain and nerves. Inf. oe. g., infra-oesophageal ganglion with 



nerves to antennae; oe., oesophagus; n. f., frontal nerve; g. 

 opt., optic ganglion; m. opt., muscles which move the eye; 

 p. f., pigment fleck; n. opt., 0[)tic nerve. 



5. Posterior part of embryo. 



6. Eurycercus lamellatus. Heart, showing the anterior bifid por- 



tion between the lobes of which is the arterial opening and 

 valve. The vaned arrows represent deeper currents while 

 the unvaned indicate superficial ones. The dotted line rep- 

 resents the position of the puls:iting membrane separating the 

 venous from the arterial currents and seen in section at (a). 



7. Daphnia similis. Anterior part of the nervous system seen from 



below, a, optic nerve; b, optic ganglion; c, frontal nerve; 

 d, nerve to antennules; e, commissure connecting upper and 

 lower oesophageal ganglion; f, nerves to antennae and mandi- 

 bles. [After Claus.] 



