NEMERTEA ENOPLA 



663 



connexion between prol)oscis pore unci mouth can be formed 

 differs in these sub-orders. 



2. That the Polystilifera exhibit the more primitive features, 

 as in most genera the proboscidian and digestive systems are 

 quite separate from each other, and the mouth even can be 

 found underneath the brain as in Biboga- and Paradino- 

 nemertes. 



3. That in the Polystihfera the Pelagica are the more 

 primitive, though a speciahzed tribe. 



Text-fig. 25. 



rkvnrh cell 



Position of testes and ejaculatoiy ducts on the ventral aide of 

 N e c t o n e m e r t e s minima (Brinkmann) (4, p. 104, Text-fig. 23). 



4. That the absence of cerebral organs, of a highly differen- 

 tiated brain, of a long much-developed stomodaeum with 

 oesophagus, of rhynchocoelomic diverticula, of metamerically 

 arranged vascular loops, are primitive features, and that 

 reduction did not cause them. 



5. That the development of the musculature of the proboscis 

 and its sheath in all Hoplonemerteans is in perfect accordance 

 with our knowledge of the anatomy of the Anopla and of their 

 embryology, and that every stage of this development from 

 the Anopla stage to the interlacing of Drepanophorus is found 

 in the different genera of Pelagica. 



6. That the blood-vascular system in the different genera of 

 Pelagica shows the development of the dorsal blood-vessel 

 from a short blind rhynchocoelomic vessel, that in some species 



