238 EDWIN S. GOODRICH. 



It will be seen from the description here given that these are 

 no ordinary excretory granules.^ On comparing them with 

 the granules found in the nephridia of other Polychsetes, we 

 find in some forms, such as Trophonia and Pectinaria, trans- 

 parent spheres containing concretions; but the latter are often 

 numerous, and are composed of irregularly aggregated smaller 

 concretions without constant shape. 



Of course, there is no direct evidence that these granules in 

 Sternaspis are of an excretory nature ; they certainly do not 

 appear to be got rid of by the animal, since the nephridium is 

 not known to open to the exterior. It is, therefore, not im- 

 possible that they may be stored up in the organ to serve some 

 further purpose in the economy of the worm. 



In the foregoing account the anterior paired brown sacs 

 have, for convenience' sake, been called nephridia. It is quite 

 possible, however, that they are not true nephridia, but peri- 

 toneal funnels peculiarly modified, and retaining but a small 

 ciliated opening into the general body-cavity. The question 

 of their exact homology can only be answered by the help of 

 embryological data which we do not yet possess. 



The same may be said concerning the homology of the 

 genital organs. Yet in this case the anatomical evidence 

 seems to point more clearly to the ducts and lobed sac being 

 formed by the modification of a pair of ciliated peritoneal 

 funnels. Cases of the overgrowth of the gonad by the funnel 

 of the genital duct (or a fold of the peritoneum), so as to 

 almost or entirely close it ofi" from the general coelomic cavity, 

 are by no means rare amongst the Coeloraata. The male 

 organs of Lumbricus offer a familiar example in which the 

 testis and genital funnel become enclosed in a sac surrounded 

 by, yet separate from, the general coelora. The peritoneal 



sont en voie de division. ... A premiere vue on pourrait prendre pour des 

 vesicules adipeuses les nombreux noyaux tres refringents de ces cellules ; 

 mais ils ne se colorent nullement par I'acide osmique, et il est facile aussi de 

 constater que la plupart d'entre eux sont en voie de segmentation " (3). 



^ The " chloragogen " granules in the cells of the intestine do not resemble 

 them. 



