PL.ATE M. 



I Fig. 1. Daphnia schcefferi^ post-abdomen of female. 



Fig. 2. '' " " ''male. 



Fig. eS. '' " male antennule. 



Fig. 4. " " brain and nerves. 



inf. oe. g. infra- cesophagal ganglion with nerves to anten- 

 nae; ce. oesophagus; n. f. frontal nerve; g. opt. optic gang- 

 lion; ra. opt. muscles which move the eye; p. f. pigment 

 fleck; n. opt. optic nerve. 



Fig. 5. Daphnia scho'fferi, posterior part of embryo. 



Fig. 6. Eurycercus lamellatus^ heart, showing the anterior bifid 

 portion 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 represents the position of the prlsatin^ membrane 

 separating the venous from the arterial curients and seen 

 in section at (a). 

 .Fig. 7. Daphnia similis^ anterior part of the nervous system seen 

 from below, a. optic nerve; b. optic ganglion; c. Irontal 

 nerve; d. nerve to antennules; e. commissure connecting 

 upper and lower oesophagal ganglion; f. nerves to antennae 

 and mandibles. 



