STRUCTURE OF THE NEPHKJDIA OF DINOPHILUS. 527 



is only shown by the refractive tubes which make them look 

 not unlike a number of pins inserted on the ends of the 

 nephridial canals. With proper lighting, however, and 

 the use of a coloured glass screen their actual outline is 

 brought into view, when they are seen to be pear-shaped 

 bodies inserted on the end of the blind nephridial canal, being 

 attached by a delicate hyaline tube piercing the nephridial 

 wall, each tube having a long flagellum in its interior which 

 passes into the lumen of the nephridial canal and down almost 

 the whole length of this canal {Qg. 2). I can find no evidence 

 of the canal itself being ciliated as Harmer (8) has described. 

 On the first nephridium I have counted at least thirty soleno- 

 cytes, but their number is possibly double this as it is impos- 

 sible to accurately count them on account of the active 

 movements of the worm. 



Collectively they form the " triangular body '•* or " ciliated 

 appendage " mentioned by Harmer (8) as being inserted into 

 the distal extremity of the nephridial canal. They by no means 

 form really a triangular body, as they can be frequently seen 

 to be spread out fan-like, and to be composed of a large 

 number of separate solenocytes. As the preparation is com- 

 pressed, however, sometimes the solenocytes become separated 

 into two distinct masses, and this would seem to happen 

 more frequently in the case of the first nephridium than with 

 any of the others (fig. 1). This appearance has undoubtedly 

 given rise to Harmer's (8) supposition that the ciliated 

 appendage is sometimes bifid, that this condition is merely 

 artificial being temporarily assumed, and that the solenocytes 

 form a single mass on the end of the canal can be easily 

 ascertained with a little careful examination. The space into 

 which these structures project, like the main portion sur- 

 rounding the gut, usually contains a few small brown granules. 

 These, during the movements of the animal under compression 

 are frequently forced in among the solenocytes, where they 

 lodge as if stuck amongst the hairs of a brush. Sometimes 

 they are seen to be forced directly against the end of the 

 nephridial canal of the point where the solenocytes are 



