24 



considerably enlarged and dividing into 2 tubes. Separated cloaca-ducts without appendages, 

 the only specimen being very young. 



East-Indian Archipelago. 1 Specimen. 



A very small animal, measuring 6 mm.; the average diameter is 0.75 mm., the length- 

 index therefore 8. The animal is represented in fig. 114, 4 times enlarged. The colour is brown. 

 The ventral groove is distinct. The animal is shining owing to the fine spicula. 



A short description of the specimen is sufficient. It quite coincides with the preceding 

 species. This holds good for all the organs, with the exception of the cloaca-ducts and the 

 pharynx. Here we have to do with a young specimen; the generative organs do not function as 

 yet ; the cloaca-ducts are separated and have a thin wall ; the receptacula seminis are absent. 

 All these divergences may be a consequence of the immaturity of the animal. Too much 

 importance should not be attached to differences, occurring in these organs. 



2 Points of difference should be observed : 

 i" The furrow in which the cloaca-opening is found, is absent here. 



2" Besides the two salivary glands the pharynx has another appendage, a fact of more impor- 

 tance, cf. figs. I 1 5 and i 1 6, sections through the anterior part of the body. In fig. 1 1 6 

 the pharynx has united with the proximal coecum of the intestine ; the two salivary glands 

 (a) merge into the phar)nx more proximally, but are free in fig. 1 1 6 and take a normal 

 course. The walls are thick and of a similar structure to those of Rhopalomenia indica 

 (cf. fig. 112). Further a small tube 6 is obvious, opening out into the pharynx more pro.xi- 

 mally. More distally (fig. 115) i divides into 2 tubes, running parallel to the salivary 

 glands but endings much sooner. Thev are of a curious structure : the wall ijresents a limited 

 number of rows of square cells, enclosing a lumen, and not perfectly fitting together ; here 

 and there something is contained in the lumen (fig. i i 7), viz ; some granular globules, which 

 however gives the impression of being parts of the cells, not a secretion. In many Soleno- 

 gastres 4 salivary glands occur. The ventral ones are long tubes, 2 in number, as in 

 Proneomenia, merging into the pharynx either separately or united : these are the tubes a 

 in figs. I 1 5 and 116. 4 Tubular ventral salivary glands have never been observed : only 

 2 ventral and 2 dorsal ones (cf. Paramenia impexa). 



These tubes 6 might also be compared to the ampullae of Rhopalomenia aglaopheniae 

 Pruvot 4, fig. 44 — 46) but the shape of the latter is round and by no means tubular, whereas 

 they open out separately. 



A third point of comparison might be presented b)- the radula-sac, the situation of 

 which corresponds to that of other forms, and which might be rudimentary here. When e. g. a 

 radula disappears the radula-sac no longer functions as such ; when increasing in size it may 

 have the appearance, which is shown here and obtain another function. To me this seems to 

 be the best interpretation ; it ])oints at the same time to its having originated from a form 

 with distichous radula (cf. the radula-sac of Dinomenia, figs. 48 — 50, 65 — 69). This suggestion 

 is the more justifiable on account of the fact, that in Rhopalomenia aglaopheniae a rudimentary 

 radula-sac also occurs (Thik.le 8, pag. 267). 



