736 PROCEEDINGS OF THE ACADEMY OF [Dec, 



thelium and the outer longitudinal muscle layer, from the brain region. 

 Gilsoa's fluid. X 601. 



Fig. 3. — Ganglion cell IV (ueurochord cell), from the ventral brain lobe. 

 X 1120. 



Fig. 4. — Sketch of living worm, natural size and color. This represents 

 the appearance of the worm in extension; the posterior end is thin and 

 flattened and the colors are dull. The light colored median line represents 

 the rhynchoccel. 



Fig. 5. — Sketch of living worm, natural size. The worm is at rest, but 

 not contracted, and the colors are brighter than in the extended s'ate. The 

 cross lines in the posterior part indicate the intestinal caica and the gonads. 



Fig. 6. — Sketch of living worm, natural size, at rest. The white spots in 

 the posterior part represent parasites. 



Fig. 7. — Supporting cell from the epithelium of the ciliated pit of the 

 cerebral organ. X 1120. 



Fig. 8.— Ganglion cell III, from the brain. X 1120. 



Fig. 9. — Ganglion cell I, from the brain. X 1120. 



Fig. 10. — A cluster of ganglion cells of type II, from the ventral brain 

 lobe. X 1120. 



Fig. 11. — Two gland cells from the epidermis of the caudicle, in an early 

 phase of secretion. X 1120. 



Fig. 12. — Portion of a cr<)ss section of the caudicle epidermis. X 604. 



Fig. 13. — A part of the circular muscle layer from the posterior end of the 

 bo ly, in longitudinal section. Flemming's fluid, iron-haematoxylin. 

 Gontr. represents the contracted fibrillar areas which occur at regular inter- 

 vals, with light non-contracted regions between. Smaller contracted streaks 

 may be seen half-way between the larger ones. X 320. 



Fig. 14. — Two supporting cells from a cross section of the body epithe- 

 lium. Flemming's fluid, saffronin, gentian violet and iodine. The stalks 

 are relatively longer than in preparations from different fixatives, x. indi- 

 cates the intracellular ciliary prolongations. X 32U0 circ. 



Fig. 15. — Cells of the body epithelium and cutis gland cells, from poster- 

 ior end of the body. The blue-staining cutis glands of this region are much 

 shorter than the red-staining glands, and both are smaller than the similar 

 glands of the anterior end. Gilson's fluid. X 604. 



Fig. 16. — Optical horizontal section of the brain and mouth region. The 

 main outlines drawn from life and diagrammatized. The blood system (in 

 red) and the oesophageal nerve commissure are reconstructed from sections. 

 X29. 



Fig. 17. — Optical horizontal section of the posterior end of the body and 

 the caudicle. The main outlines drawn from life and diagrammatized. 

 The blood system (in red) is reconstructed from sections. X 29. 



Plate XLT, Fig. 18. — Part of a cross section through the head, anterior to 

 the brain. The rhynchodajum, Rd., surrounded by four bundles of longi- 

 tudinal muscle, lid. in., occupies the centre of the section. From the interlac- 

 ing of the radial muscle fibres, r.itif., a layer of circular muscle, CM, is 

 formed, which becomes the circular muscle of the proboscis sheath, x 70. 



Fig. 19. — Part of a cross section of the brain through the dorsal comtnis- 

 sure, showing that the dorsal commissure in this ."pt-cimen is composed of 

 fibres coming from both dor.*al and ventral lobes. The attachment of the 

 proboscis to the body w.ill is also shown. X 70. 



Fig. 20. — Part of a cross section of the body through the ventral brain 

 commissure. The section is rather obliquely cut, so that the right and left 

 sides are not quite similar. X 70. 



Fig. 21. — Part of a cro.ss section of the body through the cerebral organs. 

 The section is quite oblique, so that its plane paKSses through the anterior 

 part of the cerebral organ and the ciliated pit, Oil.P., but through the pos- 

 terior end of the left cerebral organ. X 70. 



