266 E. S. GOODRICH. 



Fig. 7. — Portion of a transverse section of tlie body-wall in the region of 

 the lateral line. Z. apoch. 4 mm., oc. 4, camera. 



Fig. 8. — Longitudinal section through the longitudinal dorsal vessel, passing 

 rather to the side, so that the lumen does not appear continuous. Z., ob. D, 

 00. 4, camera. 



Fig. 9. — Portion of the vascular system, showing the manner of communi- 

 cation between the lateral dorsal and the lateral ventral vessels ; from the 

 living. 



Fig. 10. — Small portion of the dorsal blood system in the region of the 

 10th and 11th segments, greatly enlarged to show the valves ; from the living. 

 Z., oil imm. 2 mm., 4 oc. 



Fig. 11. — Diagram of the three positions taken up by the valves: a', when 

 the flow is forwards ; d', to stop the flow backwards ; and c', when they are 

 forced back. 



Fig. 12. — Diagram representing the genital organs in situ; from the 

 living and sections. 



Fig. 13. — Diagram representing the development of the sperm-sacs and 

 ovisac in an immature specimen, as seen in a solid longitudinal section ; chiefly 

 from sections. 



Fig. 14. — Transverse section of the nerve-cord passing through a septum. 

 Z., ob. D., oc. 3, camera. 



Fig. 15. — Transverse section through a ganglionic region of the nerve- 

 cord. Z., ob. D, oc. 3, camera. 



Fig. 16. — Transverse section of the nerve-cord between two ganglia. Z., 

 ob. D, oc. 3, camera. 



Fig. 17. — Longitudinal section of the thick region of the sperm-duct. Z., 

 ob. D, oc. 4, camera. 



Fig. 18. — Longitudinal section of the narrow region of the sperm-duct. 

 Z., ob. D, oc. 4, camera. 



Fig. 19. — Section through the wall of the spermatheca. Z. apoch. 4 mm., 

 oc, 4. 



Fig. 20. — Transverse section of an adult worm passing through the median 

 spermathecal pore. Z., ob. A, oc. 3, camera. 



Fig. 21. — Tranverse section of a young worm passing through the sperma- 

 thecse. It has been necessary to combine two sections to show this clearly. 

 Z., ob. A, oc. 3, camera. 



Fig. 22. — Transverse section of an adult worm passing through the median 

 spermiducal chamber and its pore. Z., ob. A., oc. 3, camera. 



Fig. 23. — Transverse section of a young worm in the same region, showing 

 the absence of a median chamber. It has been necessary to combine two 

 sections. Z., ob. A, oc. 3, camera. 



