spicula of shape D are met with : long, curved massive spicula, and amongst these also more 

 flat and broad ones. They occur in a great number of layers superposed upon each other, and 

 make with the body-wall an angle of ± 45 . The cuticula is thick and with its many layers of 

 spicula gives the impression of being the integument of a Proneomenia-species. The state of 

 preservation does not permit of any close observation regarding the mode of formation of the 

 spicula. As to the papillae, of which great numbers are present, these are formed as in 

 Proneomenia neapolitana (Thiele 8 fig. 53), but they are comparatively larger than the latter. 



A small dorso-terminal sense-knot is present on the prolongation of the hinder body. 



The ventral grove runs from the cloaca-opening as far as a point close behind the 

 mouth-slit. There are three ventral folds : one larger median and two smaller lateral ones ; 

 near the cloaca-opening there is only one median fold in the groove, which divides more 

 proximally into three folds (figs. 6 en 7). Here too the ventral groove opens behind the 

 mouth-slit into a cavity ("Flimmerhöhle" of Wirén), which is small and divided into two halves 

 by a dorso-median septum. The "vordere Bauchdrüse" (Wirén) is present in the shape of 

 transparent, thin fibrillar glandular cells, staining pale-red with carmine; they surround the 

 pharynx almost entirely. Amongst these the cells of the "hintere Bauchdrüse" (Wirén) are 

 directly discernible as little round glandular cells, staining obviously. The latter are found, 

 though slightly developed, around the ventral folds all over the animal. 



The cloaca is of a rather complicated structure. To elucidate this cf. figures 4 — 9, 

 representing schematic transverse sections, corresponding to the given lines of the reconstruction 

 fig. 11. The section after line AB (fig. 4) shows that the finger-shaped prolongation of the 

 hinder end is a fold of the dorsal body wall, open ventrally and thus enclosing a distal offset 

 of the cloaca. More proximally (fig. 5) it is seen that the cloaca itself is divided into four 

 divisions. The clorsal division a, of which the cavity in the finger-shaped appendage is a 

 continuation, is still visible in fig. 6; in fig. 7 it has made place for the rectum. Part b is a 

 paired coecum directed forwards, still visible in fig. 6 but no more visible in fig. 7. The same 

 is the case with c, a large sack-shaped coecum, directed forwards and dividing into two coeca. 

 The most considerable extension is obtained by d, which extends far forwards (fig. 8) ; this also 

 forms two coeca. So there are three pairs of coeca, running forwards ; in fig. 1 1 they are not 

 given. The cloaca is clothed with strongly ciliated cylinder-epithelium ; in the coeca d however 

 the epithelium is not ciliated and of unequal thickness, the wall being therefore undulated. The 

 case is different with the coating of b, the epithelium of which forms a great number of papillae 

 with multinucleated stalks ; the knob is often dilated vesicularly, as one of the cells swells and 

 becomes transparent. Between the papillae are found openings, in which during the animals life, 

 straight spicula are implanted (fig. 12). In Proneomenia Sluiteri Hubrecht probably describes such 

 another organ as the byssus-gland ; Heuscher recognised it in the same species ; in Proneomenia 

 vagans it also is found. The wall is to be regarded as a part of the integument, which has 

 penetrated into the interior, forming there an organ which may be subservient to copulation. 



Of gills or folds of the cloaca-wall, which might perform the function of gills, nothing 

 is present. 



Of the nervous system the only thing to be mentioned is, that it fully corresponds to 



