19 



A dorso-terminal sense-knot cannot he indicated. 



The ventral groove runs as far as the cloaca and contains 3 folds : i laro-e median fold 

 and 2 smaller lateral ones. The "vordere Bauchdrlise" cannot be demonstrated. The "hintere 

 Hauchdriise" is only slighdy developed, except around the "Flimmerhohle". A very rigorous muscular 

 bundle connects the dorsal wall of the "Flimmerhohle" with the dorsal body-wall (fig. 85, m). 



The characteristics of this form are found in the structure of the alimentary canal and o-iHs. 



Fig. 87 gives a reconstruction of the anterior part of the alimentary canal. The mouth- 

 cavity is spacious, filled wiih uiiramihed long cirrhi; the "Mundlei.sten" are comparatively small. 

 The part next to it, which may be called pharynx, is a long tube, the wall of which is strongly 

 folded, the lumen being therefore extremely small. It is encircled by a strong circular muscular 

 layer, numerous unicellular glands opening out into it. 



A well developed radula is present (fig. 88). Passing out of the radula-sac it runs 

 dorsally; then it bends to take a somewhat slanting ventral direction, on account of which it 

 can be touched twice in the transverse sections (fig. 89). Radula-teeth are met with of pointed 

 shape (fig. 88 C), or with two points (A), more comb-shaped (H and E), or con.sisting of two 

 parts above each other (F). /> may be a fragment of F, and A, C and 77 fragments of £. 

 Shape B gives the impression of being an uninjured tooth. There is only i row of teeth, the 

 radula being therefore monoserial. A distinct basal membrane carries the teeth (fig. 89). 1 

 consider this interpretation the most acce])table; perfect certainty however cannot be obtained. 

 Fig. 90 e. g. represents a section tlirougli the radula-sac with i tooth, almost of shape F. 

 But small pieces (r. /.) are moreover found in the radula-sac, lying quite lose from the said 

 tooth. Whether these are fragments or not cannot be decided. Shape A reminds of a tooth 

 entirely difterent from F but is jirobably a fragment; from the transverse sections however can 

 only be concluded that there is but i row of teeth. The radula is placed upon a far projecting 

 tongue, coated with cubical epithelium and filled with loose connective tissue ; under the radula 

 however the epithelium is multi-layered (fig. 89J. The radula-sac is surrounded by a circular 

 muscular layer, from which muscular bundles originate, running towards a number of cartilaginous 

 cells (fig. 90, c c), also mutually connected and enveloped by muscles. These cartilaginous cells 

 are very transparent and partly or entirely filled with greenish granules sometimes travelling 

 through the cells as bands. 



The salivary glands, which remain separated, spring from the lateral pharyngeal wall, 

 in front of the radula. They are of a peculiar structure and consist of difterent globular 

 accumulations of glandular cells ; narrow cells, strongly granular. Here and there a small lumen 

 is di.scernible in the globules. They produce a secretion which flows into a canal, by whicii it 

 is conveyed to the pharynx, the wall of which consists of cubical epithelium ; a tolerably strong 

 circular muscular layer surrounds it. These canals — the salivary ducts (fig. 87 .s-.^/.) — are ramified 

 several times and end therefore in some blind offsets (fig. 86 y. //.). How the matter, secreted 

 by the glandular portion finds its way to the tubes, is not clear, probably between the cells 

 of these. To a certain extent this arrangement also obtains in Rhopalomenia aglaopheniae 

 (Pruvot 4, fig. 46), were lobes of glandular cells surround the salivary glands, here unramified; 

 the opening out of the cells into the ducts is not exactly indicated (cf. fig. 92). 



