1901.] NATURAL SCIENCES OF PHILADELrillA. 703 



distance faora the lumen to the periphery of the bulb — is greater 

 than their width. The peripheral ends are considerably enlarged 

 and often irregular in outline; the luminal ends are frequently 

 produced into long slender processes that seem to take some part in 

 the formation of the stem of the bulb. The cytoplasm of the 

 peripheral (proximal) end takes a bright pink, hsematoxylin-eosin 

 stain; the distal processes, however, stain very faintly. The nu- 

 cleus is large and fusiform, but appears round in cross section, and 

 is situated in the expanded proximal end of the cell. 



After finding the terminal bulb cells so well preserved in sec- 

 tions, it seemed most probable that the long branches of vibratile 

 cilia, the " ciliary flames " (" WimperQammen, " Burger), present 

 in the terminal bulbs of other Nemerteans, might also be found; 

 but although they have been carefully looked for, they have 

 net been seen. Cilia, fig. 46, Cil., are found on the cells of 

 the nephridial duct and of the ductules, and generally in a good 

 state of preservation, so that it seems improbable that the cilia of 

 the bulbs should have been destroyed by fixation. On the other 

 hand, the analogy with the terminal bulbs of those Nemerteans that 

 have been exhaustively studied is in favor of their presence in Zy- 

 f/eujjolia also. 



The bulbs project freely into the blood vessel all along its ven- 

 tral surface, and in one case a ductule was observed that passed 

 through the vessel, so that its bulb came to lie on the opposite, 

 dorsal, surface. The epithelial lining of the blood vessel is fre- 

 quently broken and discontinuous in*' the region of the bulbs, figs. 

 46, 47, and in no place are the bulbs covei'ed by it, so that the 

 ends of the bulbs are directly bathed by the blood. The absence 

 of the blood vessel epithelium from the ends of the bulbs may fa- 

 cilitate the absorption of waste substance from the blood, and this 

 may account for the disappearance of the lining from around the 

 bulbs of the nephridia. 



No internal openings between the nephridium and the blood 

 vessel, such as Oudemans describes in Carinoma armandi, have 

 been seen. 



The nephridial ductules, figs. 46, 47, Npli.d., the slender tubes 

 that connect the terminal bulbs and the main duct, are very sinu- 

 ous, and it is probable that several terminal bulbs may connect 

 with one ductule. Some ductules are quite long, especially those 



