222 OLIGOCHAETA 



spermathecae open in a similar position behind the ventral setae of the ninth 

 segment. 



The three species of the genus are the following: 



(i) Stylodrilus heringianus, CLAPAREDE. 



S. heringianus, CLAPAKEDE, Me'm. Soc. Phys. Gen. 1862, p. 263. 

 Definition. Length, 30 mm.; number of segments, 80. Prostomium obtuse. Dorsal vessel 



without dilatation. Penis as long as half diameter of body. Hob. Geneva ; Bohemia. 

 CLAPAREDE has figured all the important organs of the body in this species. 

 A curious point is the existence of a large octaedral crystal in the spermathecae, 

 which seems to distinguish this species from the next. VEJDOVSKY found this species 

 in Bohemia. 



(2) Stylodrilus gabretae, VEJDOVSKY. 



S. gabretae, VEJDOVSKY, SB. Bb'hm. Ges. 1883, p. 325. 



Definition. Length, 40 mm. Prostomium conical. Dorsal vessel with dilatations ; hearts 

 in VI and VII ; penis nearly equal in length to the diameter of the body. Hal. 

 Bohemia. 

 This species is fully illustrated by VEJDOVSKY in his work upon the Oligochaeta. 



(3) Stylodrilus vejdovskii, BENHAM. 

 S. vejdovskii, BENHAM, Quart. J. Micr. Sci. xxxiii. p. 209. 



Definition. Length, 25 mm. ; dorsal vessel not dilated; nephridia of first two pairs extend 

 through three or four segments. Penis just greater than half diameter of tody. Hob. 

 River Cherwell, England. 

 This species (illustrated by BENHAM) is said to differ from the other two in that 



the setae are all notched. But, as these kinds of setae appear to be liable to wear, 



the difference is, perhaps, not real. The nephridia are obviously like those of 



Phreatothrix (see p. 218). 



Genus STTTROA, EISEN. 



DEFINITION. Prostomium elongated ; setae not bifid ; clitellum VII/XV ; spermi- 

 ducal glands enormously elongate, and furnished with a coating of glandular 

 cells, broken up into globular masses opening on to X ; the sperm-sacs 

 surround the spermiducal glands ; a single spermatheca in VIII. with numerous 

 branched and simple diverticula. Testes in X ; ovaries in XI ; oviducal pores 

 on XI/XII. 



