NEPHRIDIA OF CERTAIN EARTHWORMS. 401 



excellently preserved examples from Bermuda, through the 

 kindness of Mr. Shipley, Fellow of Christ's College, Cam- 

 bridge. These specimens appear to be identical with Perrier's 

 P. aspergillum. The nephridiopores could be easily ob- 

 served, as in the case ofAcanthodrilus multiporus, upon 

 the cuticle when stripped off and examined in water. I may 

 take this opportunity of saying that there are other structures 

 which might possibly be confounded with the nephridiopores ; 

 these are the impressions of sense cells upon the cuticle 1 

 which in Perichaeta often lie between the seta?. A careful 

 examination, however, soon serves to discriminate between the 

 two ; the circular bulgings of the cuticle, due to the prominent 

 sense organs, although presenting the appearance of pores 

 under a low power, are readily seen under a high power not to 

 be pores at all, while the nephridiopores are clearly holes in 

 the cuticle. 



The latter form a more or less irregular row surrounding 

 each segment and lying between the setse (fig. 12). Often 

 there are four or five between two setae. In transverse sections 

 each pore is seen to be continuous with a nephridial tubule ; 

 the actual orifice is surrounded (fig. 8) by a very few large 

 cells — smaller, however, than the cells of the epidermis ; 

 below these are smaller cells ; that section of the tubule 

 which lies within the circular muscle layer, has a wide lumen 

 whose walls are made up of excessively delicate flattened cells. 

 At the junction of the circular and longitudinal fibres the 

 duct becomes intracellular (fig. 10). The nephridial tubules 

 are abundantly supplied with blood-vessels (figs. 10, 11) in their 

 passage through the body walls. The nephridial tubules agree 

 with those of A. multiporus in the fact that the duct becomes 

 inter- cellular at the junction of the longitudinal and circular 

 muscles (cf. figs. 6 and 10). Fig. 9 represents the actual 

 number of nephridial tubules and their external orifices in a 

 small portion of the body wall ; the figure would be equally 

 correct, so far as my observations go, for any part of the body 

 wall. I should state, however, that I have at present only 

 1 Vejdovsky (13), pi. xv, fig. 13a. 



