Castle. — Rhynchobdellidse. 



PLATE 2. 



Fig. 4. G. stagnalis. Diagram showing anniilation, central nervous system, repro- 

 ductive organs (male in left, female in right half of figure), nephropores, 

 etc. The outline of the body was drawn from a whole preparation (X 

 about 16) ; everything else is diagrammatic, representing the average 

 form and position of organs as determined by examination and com- 

 parison of several individuals. 



Fig. 5. Brain of G. elegans, ventral view. From an entire preparation. X 52. 



Fig. 6. G. parasitica. Dorsal view of a young individual from Havana, Illinois, 

 partially extended. X about 10. The starlike structures indicate 

 papillie ; not all of those shown were observed in the individual figured, 

 some being supplied from the study of larger individuals in wliich the 

 papillae are more conspicuous. 



