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 smal! 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. 



,\ short description of the specimen is sufficiënt. 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 

 vet; 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 : 

 1" 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. 115 and 116, sections through the anterior part of the body. In fig. 116 

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

 («) merge into the pharynx more proximally, but are free in fig. 116 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 b is obvious, opening out into the pharynx more proxi- 

 mally. More distally (fig. 115) 6 divides into 2 tubes, running parallel to the salivary 

 glands but ending much sooner. They are of a curious structure : the wall presents 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. 1 1 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. 1 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 b 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 by 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 points at the same time to its having originated from a form 

 with distichons 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 (Thiele 8, pag. 267). 



