ESC ANS MON (Ol PISTEN 
. 15.—Perionyx bainii;, penial seta; x ca. 300. 
15. —Megascolex escherichi var. papillifer ; genital field;  , male aperture. 
17.—Megascolex campester ; spermatheca. The appendages on the upper swollen 
part of the duct are micronephridia. 
18.—The same; distal end of a penial seta. a., as seen under the microscope, X 
about 400. b., represents what would probably be seen if the end of the 
seta could be rotated through a right angle; but this view is not obtained, 
since the setae, owing to the curve of the shaft, lie on the slide in the 
position of a. | 
19.—Megascolex hortonensis; genital area. cht., clitellum; g. f., the surface of 
the thickened genital field; pap., flat, slightly raised papillae; pen., 
penis; pit., depression on segment xviii; xvii—xix, the corresponding | 
segments. 
20.—The same; spermatheca. 
21.—Megascolex kempi ; spermatheca. 
22.—Megascolex varians var. insolitus; spermatheca. 
23.—The same; distal end of penial seta; x220. The whole of the portion 
which is clothed with spines is shown. 
24.—Megascolex sextus, penial seta, a., showing general shape; b., more highly 
magnified (x 300) distal extremity. 
25.—Megascolex polytheca; spermatheca, in glycerin after clearing. 0. v., blood- 
vessel running along its side ; cav., portion of cavity containing only gran- 
ular matter ; ep., epithelium lining cavity and duct; x., transparent mass, 
filling greater part of cavity ; x 90. 
