NOTES ON ACANTHODRILOID EARTHWORMS. 309 
family, but it isto be regretted that we have received no detailed 
account of the anatomy of this and the other interesting forms 
which have been briefly described by him.! 
1 ¢ Proc. Zool. Soc.,’ 1886. 
EXPLANATION OF PLATES XV and XVI, 
Illustrating Mr. W. Blaxland Benham’s “ Notes on Two 
Acanthodriloid Earthworms from New Zealand.” 
Neodrilus monocystis.—Fies. 1 to 13. 
Fic. 1.—Dorsal view of anterior end of body, showing the character of 
the prostomium (pr.), arrangement of chete (d. ch.), and position of the 
nephridiopores (ze. 0.) in these somites. 
Fig, 2.—Ventral view of the somites in the neighbourhood of the genital 
pores. ze. 0. Nephridiopores. prst.p. Pore of the prostate. sp. p. Sper- 
miducal pore. v. ch. Ventral chete. 
_ Fie, 3.—General anatomy, as seen when the worm is opened in the usual 
way; from the dorsal surface. app. Appendix of spermatheca. d.v. Dorsal 
vessel. giz. Gizzard. /.. One of the lateral hearts. ze. Nephridium. 
pe.d. Penial duct. pe.s. Sac with penial chete. prst. Prostate. sp. s!. 
Anterior sperm-sac. sp. s*. The most posterior (third) sperm-sac. spth. ~ 
The main sac of the spermatheca. 
Fic. 4.—A transverse section of the worm behind Somite xxx, showing 
the general squareness of the worm, the position of chate, and of the nephridia. 
It would be unusual to find the asymmetry of the last structures as repre- 
sented in the figure. a. Separation of dorsal muscle bundle into two lateral 
halves. 4. Lateral muscle bundle. c. Ventral muscle bundle. d. Accessory 
muscle bundle, separated from ¢ by penetration of a nerve into the body- 
wall. d.ch. Dorsal chete. d. x. Dorsal nephridium. d.v. Dorsal blood- 
vessel. m. Band of muscle passing from the dorsal to the ventral bundle of 
cheete, and acting as their retractor. NV. Nerve-cord. v. ch. Ventral chete. 
v. nm. Ventral nephridium., ».’v. Ventral blood-vessel. 
Fie. 5.—The inner surface of body-wall (rather more than half the worm 
is represented), to show position of the nephridia in consecutive segments. 
Letters as in Fig. 4. 
