Species of the genus aulodrilus* . 969 



EXPLANATION OF THE PLATES. 



JExplanation of Letters used in Figures. 



a. amis ; atr. atrium ; ap.at.d. aperture of atrial duct ; atr.d. atrial duct ; 

 h.v. blood-vessel; h.w. bodj'-wall ; c. cuticle; c.c. central chamber ; cl. clitellum; 

 coem.s. ccelomic (muscular) sac ; c.m.f. layer of circular muscle fibres ; c.s.s. cavity 

 ofsetalsac; d.h.v. dorsal blood-vessel ; d.atr.d. distal portion of atrial duct ; e.gl.c. 

 epidermal gland cell ; fem.f. female funnel ; gl.c. sland cell ; gl.pe.ss. glands in 

 connection with penial setal sac ; int. intestine ; l.^yi.f. layer of longitudinal muscle 

 fibres ; l.p.-w. lateral portion of partition wall ; m. muscles ; nieg.n. meganucleus ; 

 n. nodulus of seta ; o. opening of vas deferens into atrium ; oes. oesophagus : 

 ov. ovary; ovis. ovisac; p.atr.d. proximal portion of atrial duct; p.c. peritoneal 

 cells; pe.s. penial seta; pe.s.s. penial setal sac; per.c. peripheral chamber; 

 ph. pharjaix; pr. prostate; pro. prostomium ; pr.s. prostate secretion; prolif. 

 proliferating cells ; p.w. partition wall ; s. seta ; se. secretion ; sep. septum 6/7 ; 

 s.f. seminal funnel; sp. sperms; sp.ch. spermiducal chamber; sp.s. sperm-sac; 

 spth. spermatheca; spth.op. spermathecal opening; v.n.c. ventral nerve cord; 

 vas.d. vas deferens : v.b.v. ventral blood-vessel : v.p.iu. ventral portion of partition 

 wall. 



[Pigs. 1-12 illustrate Aulodrilus kaslii and fig. 13 Aulodrilus stepJiensoni. 

 All the figures except 1, 3, and 13 are drawn with camera lucida.] 



Pig. 1. Ventral view of anterior portion of the worm showing spermathecal 

 openings in the 6th and spermiducal chamber in the 7th segment. 

 Penial set^ and apertures of the atrial ducts lie in the spermiducal 

 chamber. X ca. 95. 



Pig. 2. Transverse section through the penial setal sac. X 220. 



Pig. 3. Semi-diagrammatic, compiled from several successive longitudinal sections 

 showing the genital organs. X ca. 120. 



Fig. 4. Transverse section of the body through the spermiducal chamber and its 

 opening. X 120. 



Pig. 5. Transverse section showing the prostate opening into the atrium. The 

 prostate and atrial epithelial cells have mostly lost cellular structure and 

 are converted into the secretion. X 390. 



Pigs. 6 & 7. Longitudinal sections through the prostate, atrium, and ccelomic sac. 

 The prostate cells are disorganized, having lost their structure, and the 

 secretion passes in a mass into the atrium. The atrial cells have also 

 lost their entitj% being replaced by the secretion. X 390. 



Pigs. 8 «& 9. Transverse sections in the spermathecal region. The coalomic cavitj'' 

 in the 6th segment is divided 1)3^ a partition wall into a central chamber 

 and a peripheral portion. In fig. 8 one spermatheca is opening to the 

 exterior. X 95. 



Pig. 10. A part of section in fig. 8 highlj' magnified. The partition wall consists 

 of a circular la3er of muscles in the middle with a laj'er of parenchy- 

 matous cells on either side. X 540. 



Fig. 11. Terminal portion of the body. The part just in front of the anus shows 

 no signs of formation of new segments. X 97. 



Pig. 12. Ciliate astoma parasites. 



Fig. ]3. Ventral view of a part of the bodj' in A. stephensoni showing spermathecal 

 openings in the 9th and shallow spermiducal chamber with penial setoe 

 and openings of atrial ducts in the 10th segment. X ca. 95. 



