536 /. PERCY MOORE. 



EXPLANATION OF PLATE XXX. 



Fig. 1 6. Dorsal view of the ventral ganglia of the head, showing also the an- 

 terior termination of the supra-neural blood vessel. X 250. Reduced from a 

 camera lucida drawing of a living specimen. 



Fig. 17. Dorsal aspect of the supra-oesophageal ganglion, and termination of 

 the dorsal blood-vessel of the same specimen. X 250. sg, principal, and j^S 

 accessory lobes of the ganglion; cc, circum-oesophageal commissure; va * and va'^, 

 the 1st and 2d vascular arches. 



Fig. 18. Transverse section through the ventral nerve cord and ganglia of the 

 8th somite. Biondi-Ehrlich. X 500. In, In, lateral nerve trunks to body walls; 

 g, gangUon cells ; ^S larger ganglion cells; m, muscular sheath of the nerve cord; 

 sv, supra-neural blood vessel. 



Fig. 19. The entire atrium of a mature worm, removed from the body and ex- 

 amined in a fresh condition under slight pressure. X195. Camera lucida out- 

 lines, but the histology is purely diagrammatic, and is introduced only to differen- 

 tiate the various regions. Viewed from the left side, vd'^ and vd^, the anterior 

 and posterior pairs of vasa deferentia; sv, glandular spermatic vesicle; sv'^, mus- 

 cular spermatic vesicle; Ini, longitudinal, and cm, circular muscle coats of the 

 penis sheath and copulatory bursa; jj, sub-epithelial space ; /^, penis; ^, bursal 

 glands ; e, lining epithelium of bursa. 



Fig. 20. The same seen from in front ; the glandular sperm sac is displaced. 

 Lettering as before. 



Fig. 21. Transverse section of a vas deferens, showing the muscle cells and 

 lining epithelium. Haem. X 840. 



Fig. 22. Transverse section across the glandular sperm sac. Osmic acid and 

 alum cochineal. X 500. 



Fig. 23. Section through the point of union of the glandular and muscular 

 sperm sacs, showing the abrupt change in the character of the epithelium, and the 

 termination of the circular muscle coat. The section cuts the muscular sac trans- 

 versely and near the side; and the glandular sac longitudinally and almost through 

 its axis, ge, glandular epithelium ; e, non-glandular epithelium ; m, muscular coat ; 

 /, peritoneum. 



Fig. 24. Vertical transverse section of the copulatory bursa, through the 

 glands. The penis is abnormally retracted. Borax carmine. X 500. g, g, bursal 

 glands; e, epithelium; Im, Im, longitudinal muscle coat; tm, circular muscles; 

 ^e, penis. 



