564 F. W. GAMBLE AND J. H. ASHWORTH. 



of the lieait. The position of the first gill is indicated internally by the 

 afferent and efferent branchial vessels {Br. Jp and Br. Tiff}). X \\. 



Fig. 45. — Dissection of a medium-sized female specimen of A. ecaudata 

 from Port St. Mary (April, 1897), to show the general characters of the 

 internal anatomy. Note the three anterior diaphragms, the buccal muscula- 

 ture, the septa in the posterior portion of the animal, the oblique muscles, the 

 alimentary canal, the vascular system, the nephridia, and the ovarian processes. 

 The second nephridium is supplied with blood by a small vessel from the 

 dorsal longitudinal vessel (Z>. L. F.). The position of the first gill is shown 

 internally by the afferent and efferent branchial vessels {Br. Aff\ Br. Eff.^). 

 The first two efferent branchial vessels are accompanied by a thin band of 

 connective tissue, the representative of the septum of the following segments. 

 The septa and oblique muscles are present to the posterior end. The first 

 nephridium does not bear gonads. The ovarian processes attain a larger size 

 in larger specimens. The last twenty-seven segments of the worm are omitted. 

 X 2." 



PLATE 26. 

 Pig. 46. — One of the nephridia of the right side of a medium-sized female 

 specimen of A. ecaudata (Port St. Mary, Isle of Man, April, 1897) seen 

 from the ventral aspect. The nephrostome (red) is formed of two lips, a 

 deeply notched ventral one {Nphm. V.) and a dorsal one {Nplim. D.), bearing 

 numerous digitiform ciliated vascular processes. The network of blood- 

 vessels upon the nephrostome is somewhat closer than shown in the figure. 

 Note the blood-vessels with blind dilated ends on the ventral lip. The 

 secreting portion of the nephridium and the vesicular bladder are covered by 

 a network of blood-vessels. The genital strand arises on the inner side of the 

 funnel, and runs parallel to, and applied to, the secreting portion of the 

 nephridium. It is pierced axially by the gonidial vessel {G. V.). On the 

 outer side of the ventral lip of the nephrostome there is a deeply staining 

 strand of cells {Sir.), which probably gives rise to coelomic corpuscles. The 

 Ion"- fiuo'er-shaped outgrowths from the genital strand contain ova in all 

 stao-es of development. Each is supplied by one or more vessels — branches 

 of °he gonidial vessel (see Pigs. 51, 52). The processes are considerably 

 larf^er iu mature specimens than in the specimen drawn. X 22. 



Fig. 47.— Sixth right nephridium of a large female specimen of A. ecau- 

 data (from Port St. Mary, April, 1897), seen from the ventral aspect. The 

 ova, having been discharged from the ovarian processes into the cojlom, have 

 been taken up by the nephrostome and passed into the bladder of the 

 nephridium, causing the thin-walled sac-like diverticulum shown in the figure. 

 This sac is full of large ova. There were similar vesicles attached to the 

 bladders of the fifth and sixth nephridia of the left side. X 8. 



Fig. 48.— A nephridium from the right side of a male specimen of A. 

 ecawdata (Port St. Mary, April, 1897), seen from the ventral aspect. 



