258 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF PLATE V. 

 Pontoscolex corethrurus (Fr. Muller) mexicanus, subsp. nov. 



Fig. I. Specimen natural size. 



Fig. 2. Anterior somites, ventral view. 



Fig. 3. Anterior somites, side view. The nephropores are seen to be in 

 front of the setae cd. Setse cd m II are further apart, larger and 

 also more dorsal than the corresponding setae in other somites. 



Fig. 4. Anterior somites, side view. Prostomium retracted. More mag- 

 nified than figs. 2 and 3. 



Fig. 5. Clitellar somites, side view, showing the tubercula pubertatis and 

 the enlarged glandular area around the setae. 



Fig. 6. Part of the body-wall of the anterior somites spread out, showing 

 the location of anterior setae. There is no nephridium in III. 

 Setae cd in II are fiirther apart, larger and more dorsal than those 

 in III, IV, etc. 



Fig. 7. A penial seta from clitellum. 



Fig. 8. One of the spermathecae. 



Fig. 9. Longitudinal section of the anterior somites. Zeiss a 2, Oc. 12. 

 {s) Much enlarged septum III/IV; (m) muscles to which are 

 attached the suprapharyngeal glands and muscles connecting this 

 septum with the body-wall. The former are fastened to the very 

 large septum separating III/IV. 



Fig. 10. Part of the pharynx, showing the discharge-pockets of the unicell- 

 ular glands. 



Fig. II. Longitudinal section of the body-wall of somites VII and VIII, 

 passing through the spermathecal and nephridial pores, showing 

 the opening of the former in the posterior part of the somite, in 

 front of the septum separating VII/VIII. Zeiss D., Oc. 2. 



Fig. 12. A nephridium dissected out, from a somite next posterior to clitel- 

 lum; gl. p., glandular pouch; br., bridge of nephridium. 



Fig. 13. The part surrounding the glandular pouch of another nephridium; 

 gl. p., glandular pouch; /., duct to the folds; n. d., narrow duct 

 connecting with the nephrostome. 



Fig. 14. Section of the nephridial sphinxter at its interior end. 



Fig. 15. Section of the nephridial sphinxter at its outer end, showing a cili- 

 ated inner epithelial lining. 



Fig. 16. A part of the former figure more highly magnified. 



