738 EDWIN S. GOODRICH. 



the solenocytes, on the surface of the nephridium, by the 

 action of which the surrounding liquid is kept in motion. In 

 Alciope cantraiuii these cilia work regularly between the 

 tubesj placed in short transverse rows to facilitate this move- 

 ment (figs. 3 and 4). The proximity of the solenocytes to 

 the ciliated persistent genital funnels, in Nephthys and 

 Glycera, and the general circulation of the coelomic fluid in 

 the latter genus, probably render the development of external 

 cilia unnecessary in these forms. 



With our present lack of knowledge of the development of 

 the solenocytes, we can do little more than make a rough 

 guess at their homology. As has been shown above, p. 735, 

 there seems to be little doubt that the nephridia of the 

 Phyliodocids, Nephthyids, and Glycerids are primitive in 

 being closed internally, that they have never been otherwise 

 than closed, and must, therefore, be compared with the 

 " protouephridia^' of the Platyhelminths, Eotifers, and 

 Nemertines. Anyhow the solenocytes themselves can be 

 more readily likened to flame-cells than to any other struc- 

 tures described in the excretory organs of the Annelids, or 

 their allies.^ Indeed, if we carefully compare these cells with 

 the flame-cells described by Burger (1 a) in the Nemertines, 

 the resemblance is seen to be more than superficial. In both 

 cases there is the same tendency to the grouping of the cells 

 in bunches, the same shape and position assumed by the cell- 

 body at the extremity of a narrow canal in which the cilia 

 work ; and the processes drawn by Biirger as arising from 

 these cells, may perhaps be compared with those seen in 

 Nephthys.^ 



^ Tbere is a strange resemblance between the solenocytes and the peculiar 

 cells described by Boveri as surrounding the openiugs of the excretory tubules 

 in Amphioxus. Some years ago, I examined these tubules in fresh specimens, 

 and came to the conclusion that the resemblance is only superficial. In 

 Amphioxus, the straight processes converging towards the coelomic openings 

 appear tobesolidprotoplasmicrods (perhaps modified cilia), not tubular 

 structures opening into the lumen of the kidney-tube, as in the case of 

 solenocytes. 



"^ In this general discussion I have made no mention of the solenocytes in 



