FISSION IN NEMERTINES. 31 
Fic. 9.—A somewhat diagrammatised view of the muscle-fibres and con- 
nective tissue in the region of one of the “septa.” m. Muscle-fibres. 
c.f, Connective-tissue network, through the meshes of which the fibrils pass: 
the network is denser in the region of the “septum” than elsewhere. 7! 
Nucleus of ‘‘ septum.” 
Fic. 10.—Transverse section of the worm (mag. B 2,cam.). ep. Epi- 
dermis. 4.¢. Basement tissue. 4v. Blood-vessel. circ. Circular muscles 
of body-wall. 7g. Longitudinal muscles. zz¢. Intestine. izé.c. Circular muscle 
of intestine. zz¢./y. Longitudinal muscle of intestine. Pr. Proboscis. P.ep. 
Outer epithelium of proboscis. RA. Rhynchocel. R.ep. Epithelium of 
rhynchocel. rh.c. Its coat of circular muscles. WV. Lateral nerve-stem. 
x. Streak of tissue resembling connective tissue interrupting the longitudinal 
muscles dorsal (? decussation of r/.c.). y. ‘Connective tissue” near blood- 
vessel. 
Fic. 11.—View of section across lateral nerve-stem. 4.¢. Subepidermic 
basement tissue. circ. Circular coat of muscles. ch. Neurochord, with 
distinct membrane and (?) coagulum within. m!. Outer membrane (? neuri- 
lemma). #', Inner membrane, separated at one point by a space (sp.), probably 
due to shrinkage. gy. Nuclei of nerve-cells. .s. Nuclei of sheath. p. 
Punktsubstanz in the meshes of nerve-cord. D.V. indicate the dorsal and 
ventral surfaces of the nerve-cord. 
Fie. 12.—A portion of a section across the region A to show the ripe 
ovary. ov. Ovary. O. A ripe ovum. w. Wall of ovary. s. “Septum.” 
b.m. Basement tissue exposed after the rupture of the epidermis. 
