640 ANATOMY, HISTOLOGY, AND AFFINITIES OF PHREORYCTES. 



9. Schlotthauber. Beitriige fiir Helminthologie, Amtliche Bericht uber 31 te Versammlung deutscher 

 Naturforschcr und Artzte zu Gottingen, 1861. 



10. Timm, R. Beobachtungen an Phreoryctes Menkeanus, Hoffm. und Nais, Arbeiten aus dem zoolog- 



zootom. Institute in Wiirzburg, Bd. vi. (1883). 



1 1. Vejdovsky, F. System und Morphologie der Oligochaeten, Prag. 1884, p. 48. 



12. Da Rossi, J. Phreoryctes Menkeanus, Jahresbericht der Zool. Section des westfalischen pro- 



vinzial Vereins fiir Wissenschaft und Kunst, xv. p. 29. 



B UPON OTHER OLIGOCH^TA. 



1. Beddard, F. E. On certain Points in the Structure of Clitellio (Olaparede), Proceedings of the 



Zoological Society of London, 1888. p. 485. 



2. Bekgh, R S. Zur Bildungsgeschichte der Excretionsorgane bei Criodrilus. Arbeiten aus der 



Zool. Zoot. Institute in Wiirzburg, Bd. viii. p. 223. 



3. Vejdovsky, F. Anatomische Studien an Ehynchelmis limosella, Zeitschrift fiir wissenschaftliche 



Zoologie, Bd. xxvii. (1876). 



4. Vejdovsky, F. Entwickelungsgeschicbtliche Untersuchungen, Heft, i., Prag. 1888. 



EXPLANATION OF PLATE. 



Fig. 1. Lateral view of Phreoryctes Smithii (anterior segments), to illustrate the principal external 



characters, cf, orifices of spermatheca ; £, male ; £, female generative apertures ; 



cl, clitellar segment. 

 Fig. 2. Longitudinal section through genital region, t, testes ; vd, vasa deferentia ; o, ovaries ; 



od, oviducts ; sp, intersegmental septa. 

 Fig. 3. Longitudinal section through oviduct, ch, chitinous membrane lining orifice of duct. The 



cells here are not ciliated. 

 Fig. 4. Spermatheca as seen on a dissection of the worm, sp, spermatozoa in its interior. 

 Fig. 5. Transverse section of spermatheca. b, clumps of granules secreted by cells, and serving 



to agglutinate together the spermatozoa ; n, nuclei ; a, muscular sheath. 

 Fig. 6. Setae, a, of dorsal ; b, of ventral pair, drawn to scale. 

 Fig. 7. View of four segments in the posterior region of the body, to illustrate the vascular trunks. 



d, dorsal vessel ; v, ventral vessel ; n, nerve cord. 

 Fig. 8. Transverse section of one of transverse vessels of anterior segments, e, epithelium lining 



the vessel. 

 Fig. 9. Longitudinal section of one of the transverse vessels of anterior segments, m, muscular coat. 

 Fig. 10. One of transverse vessels of third segment, p, peritoneal cells forming a thick coating 



round the vessel. 

 Fig. 11. Section through 14th segment, a, ripe ova ; n, their nuclei ; sp, intersegmental septum ; 



os, wall of egg-sac. 

 Fig. 12. Section through body-wall to illustrate proportionate thickness of e, epidermis; m', trans- 

 verse muscular layer ; m, longitudinal muscular layer. 



