106 WILLIAM BLAXLAND BENHAM. 



a. Ventral setse. 6. Lateral setae, c. The nephridiopores. d. The pores of 

 the sperm-ducts. 



Fig. 13. — Setse. Nat. size, 0'65 mm. a. Prom the preclitellar region. 



b. One of the ventral setae from the clitellum. 



Fig. 14. — The worm opened along the dorsal surface to show its general 

 anatomy. (X 1^.) a. Prostomium. b. Pharynx, c. (Esophagus, d. Pro- 

 ventriculus. e. Gizzard. /. Intestinal glands. a. Tubular intestine, h. 

 Pouched intestine, j. Sacculated intestine. k. Ventral caeca, at the 

 junction of the pouched witli the sacculated intestines. /, /. Nephridia. m, m. 

 Spermathecse. «,»'. Seminal reservoirs. j9. Dorsal blood-trunk. 



Fig. 15. — The junction of {a) the pouched with (c) the sacculated intes- 

 tine, seen from the ventral surface in order to show the origin of the ventral 

 cseca {b). 



Fig. 16. — A portion of the pouched intestine, the dorsal wall of which 

 has been removed, seen from above, a. The ventral wall of the axial lumen 

 of the intestine, b. A pouch, c. The glandular (?) ridge at the junction of 

 a pouch with the axial portion. 



Fig. 17. — The alimentary tract has been removed to show the genital 

 organs, nephridia, &c. (x 2.) The seminal reservoirs have been removed 

 from the left side ; the anterior nephridia have been drawn aside to show 

 more clearly the somites to which they belong. The posterior nephridia are 

 also somewhat displaced, a. Prostomium. b. Cerebral or supra-pharyngeal 

 ganglia, c. First ventral ganglion, d. Ventral nerve-cord. f,f. The sper- 

 mathecse (there should be lines separating the spermathecse from the nephridia 

 where they dip into the body wall, on the right side), g, g. The seminal 

 reservoirs of the right side. h,j. The anterior and posterior ciliated rosettes. 

 A. The sperm-duct. /. Position of the sperm-pore. «, ri^, nJ. The nephridia, 

 of which M^ — n'' are somewhat different from the following ones. p. The 

 pyriform vesicles, q, r. Interruptions in the muscular coat of the body wall 

 for the ventral and lateral setae respectively. 



Fig. 18. — One of the posterior nephridia. a. The vesicular diverticulum. 

 b. The tubule, c. The entrance of the tubule into the neck of the vesicle. 

 d. The duct leading to the nephridiopore. e. Nephridial funnel. 



Fig. 19. — A nephridial funnel. 



Fig. 20. — A diagrammatic transverse section through the body to show the 

 relative positions on one side of the pyriform vesicle, and on the other of the 

 nephridiopore with the setae. 1, 2. The ventral couple of setaj. 3, 4. The 

 lateral couple of setae, a. Pyriform vesicle, b. Its external pore. «. 

 Nephridial vesicle, o. Nephridiopore. 



Fig. 21. — A transverse section through a pyriform vesicle, a. Membrane 

 forming the outer wall. b. Granular substance, c. Columnar epithelium 

 lining the lumen, d. lumen. 



