EXPLANATION OF PLATE XXXII & Continued, 
very rarely attain this size in the lateral trunks, nl. Nervous layer en- 
sheathing the body (see Plate XXIII, fig. 12, of this volume), np. Ner- 
vous process penetrating among the muscles. 
Fig. 7. — Oblique section (transverse horizontal) through another speci- 
men of the same species. Letters as in fig. 6. set. The layer of connec- 
tive tissue between the fibrillar and the cellular nerve-tissue. These two 
figures and the following drawn with Siebert Krafft’s immersion No. vii. 
Fig. 8. — Part of the nervous sheath in a transverse section of a large 
specimen of Cerebratulus marginatus. Letters as in figs. 6 and 7. The 
radial fibres are omitted in this figure. 
Fig. 9. — Longitudinal section through the brain and the nervous sheath 
of Cerebratulus urticans, to show the way in which the latter abuts upon 
the former, b. Brain-lobes, nl. Nervous layer, p. Outline of section 
through the proboscis, c. m. Circular muscular layer, l. m. Outer longi- 
tudinal muscular layer, i. m. Inner longitudinal muscular layer. 
Fig. 10. — The same for Langia formosa. b. Superior and posterior 
brain-lobes, n. Lateral nerve, obliquely cut. 7tp. Nervous process pene- 
trating into the longitudinal muscles. 
Fig. 11. — Part of the fibrillar nerve-sheath {nl.) with ganglion-cells of 
the foregoing preparation more strongly magni^ed. The process {np.) is seen 
to have essentially the same character as the fibrillar layer itself, and to be 
provided with several nerve-cells as well. 
Fig. 12.— The nerve-sheath seen from above in a horizontal section 
through the back of Cerebratulus pantkerinus. nps. Median dorsal nerve 
(nerve for the proboscidian sheath), nl. Fibrillar plexus with nerve-cells. 
nc. Peripheral processes from the nerve-sheath radially penetrating the 
muscular layers, rf. Radial fibres (cf. figs. 6 and 7). 
Fig. 13. — A surface section through the longitudinal muscular sheath 
(L. M.) just above the nervous layer, with elliptic canals {?ic.), more or less 
regularly arranged in transverse rows for the passage of the periphera 
processes of the nervous sheath. These processes show, also in this sec- 
tion a fibrillar structure, with nerve-cells imbedded in it. rf. Radial fibres. 
