292 



THE INVERTEBRATA 



form a useful supplement to work with Lumbricus in understanding 

 oligochaet organization. 



d.i.v. 



Fig. 201, 



Fig. 202. 



Fig. 201. Dorsal vessel oi Lumbricus to show connections and valves. After 

 Johnston, d.v. dorsal vessel ; vessels leading to dorsal vessel ; d.i.v. from sub- 

 intestinal vessel, p.v. from subneural vessel (parietal vessel); sep. septum; 

 va. valves open with dilation and va. closed with contraction of the dorsal 

 vessel. 



Fig. 202. Stylariaproboscidea. Original. Dorsal view. /ew. median prostomial 

 process ; cr. crop ; e. eye ; M. mouth ; ph. pharynx ; oe. oesophagus ; int. intestine 

 (stippled); sep. septum. The four anterior segments have hooked ventral 

 chaetae {ch.v.) only, the rest with long dorsal hair chaetae (ch.d.) as well. 



From the above account it will be seen that Stylaria differs from 

 Lumbricus not only in its small size and transparency but also in the 

 number and appearance of the chaetae — which give it a certain 



