that of Proneomenia acuminata (Wirén, 6 b , pag. 81). Only the sublingual commissure cannot 

 be pointed out with certainty, and the commissures between the ganglia posteriora superiora 

 and inferiora are wanting here. 



For the structure of the digestive organs see reconstruction fig. 13. The mouth-cavity 

 is spacious, coated with cubical epithelium and opening into the exterior through an almost 

 perpendicularly placed mouth-slit. In the mouth-cavity we find ciliated "Mundleisten" (Wirén), 

 enclosinc numerous cirrhi. In fig. [3 these cirrhi are not indicated; they are found in cavity a. 

 They are broad folds of the mouth-epithelium, sometimes ramified at the basal portion. The 

 cytoplasma of the constituent cells is finely-granular and stains pale-violet with carmine ; at the 

 basis of these cells there are bigger or smaller granules, sometimes dilated vesicularly ; these 

 an- of a brisfht green colour. The whole of the epithelium of the cirrhi themselves is filled 

 with these green globules, colouring the cirrhi in the sections dark green. This points probably 

 towards a strong secretory function of the cirrhi, though nothing like a secretion can be 

 perceived. Around the mouth-cavity there are numerous strong ganglia, in continuity with the 

 cerebral ganglion through two strong nerves. A tenuous network of nerves connects these ganglia 

 and forms a network all around the mouth-cavity, sending numerous branches towards the cirrhi. 

 This points at the same time towards a strong sensory function. 



The pharynx (/) here I follow the division of Simroth (7) - - invaginat.es some 



way into the mouth-cavity and has a considerably folded wall, encircled by a strong circular 

 muscular layer ; these muscles are especially strong in the fold (ó). No special glands open 

 int" the pharynx. 



A very strongly made radula is present. As usual the structure cannot be closely 

 investigated, the teeth having been seriously injured in the cutting of the sections. I therefore 

 isolated the radula with Eau de Javelle and put it without damage into glycerin ; so I can give 

 the exact structure. It consists of 12 rows of tolerably narrow conical teeth, directing their 

 somewhat curved points backvvards (tig. ijc). They are all of equal size except those of the 

 two middle rows, which are broader. The teeth stain pale-red with carmalum, but the strong 

 basal-membrane, upon which they are placed, does not stain at all. In fig. 17(7 and b and in 

 fig. 1 3 is representecl what is seen of the radula in the sections. In some specimens however 

 the rows of teeth reach the number of 18. This form of radula most resembles that of Proneomenia 

 vagans (Thiele 8, fig. 100, 101). This is the most strongly made radula which has been 

 observed in Solcnogastres ; fig. 13 gives the relative size. In all the other species, possessing 

 a polystichous radula, this is much smaller and less developed. There can hardly be any question 

 here of its being rudimentary. This is indeed the case with the tongue ; the radula is sustained 

 upon a single epithelium-layer. Fig. 17 gives the radula-sac a, in which new teeth are being 

 formed. The: newly formeel teeth are easily discernable as dark-coloured elevations upon the 

 al membrane, which is to be considered as a cuticular formation. The teeth touch each other 

 at the basal extremities. 1 ■ irst the radula takes its course proximally; then it bends, runs 

 ventrall) to turn again and to run proximally once more. At the second turning-point the 

 epithelium is thickened and forms pouch b built up of long slender epithelium-cells. In this pouch 

 no formation of teeth takes place, which could hardly be expected ; cuticula is formed here, 



