252 ELLIOT ROWLAND DOWNING. 



There is need of amendment in the description and figures of 

 the form of the nephridia of the genus. The funnels, in par- 

 ticular, are much more symmetrical, in some species, than they 

 have heretofore been shown. The usual technique is at fault in 

 distorting them. The funnels are attached to the oblique muscles 

 in A. Claparedii, A. cristata and A. marina. When the worm is 

 opened and pinned out for dissection, the strain on these oblique 

 muscles or on the connecting blood vessels of the other species, 

 pulls the funnels throughly out of shape. It is, therefore, well 

 to stupefy the worm by adding, drop by drop, seventy per cent, 

 alcohol to the smallest quantity of sea water that will cover the 

 worm in a long narrow dish. Then when the muscular walls are 

 relaxed, the body cavity is injected by means of a hypodermic 

 syringe or a fine pipette, until the walls are well distended with 



C.P 



FIG. 3. Dorsal view of the second left nephridium of Arenicola cristata, X 3- 

 C.P., ciliated plates. D.L., dorsal lip. G.V., gonadial blood vessel. O.M., 

 oblique muscle. 



FIG. 4. Ventral view of the anterior portion of second left nephridium of Areni- 

 cola cristata, ><3- D.L., dorsal lip. V.L., ventral lip. 



the fixing agent. (Kopsch fluid answers well.) The whole worm 

 is then placed in the fixing fluid. The nephridia are thus har- 

 dened without distortion and when dissected out later show their 

 proper form. 



The figures of the funnels or entire nephridia of each of the 

 species are shown in the accompanying figures. The funnel 

 of A. cristata (Figs. 3 and 4) is the most complicated and at 

 the same time the most symmetrical in the genus. It is flat- 

 tened, with a broadly sagittate or hastate form. Its dorsal lip, 



