490 ^' C- J- Vosmaer 



section througli a whole colony and may show how far the septa vaiy 

 in one animai. The canal s and lacunae formed by the ana- 

 stomosi» of the septa thus are morphologically quite 

 another thing than those large exeurrent ones. Thelat- 

 ter develop as ramifications, »Ausstülpungen« of the 

 main exeurrent one growing into the Sponge-mass, the 

 former on the contrary are remains of the original wide 

 cloacal-cavity. In flat specimens I now and then saw membranes 

 Crossing the cloaca and thus uniting both sides of it (fig. 8 PI. 28), but 

 I never saw this happen in a way as Haeckel illustrates of his Leu- 

 cetta pandora (1. c. III. fig. 3 J, c T. 22). 



Haeckel considers the entogastric septa as «Brutkapseln« or 

 »Fruchtbehälter«. I can hardly believe they have this function. Which 

 advantage the Sponge may have of it I do not know. If we may hold 

 on Polejaeff's opinion that also the entodermic epithelium cells take 

 in food, the advantage would be that the surface which is ab le to de 

 so , is enlarged in proportion to the mesoderm. That an overdevelop- 

 ment of the septa may lead to lipogastria seems to be clear. 



Histologically the septa possess the same Clements as the inner 

 parts of the Sponge-body. They consist of connective tissue lined with 

 flat epithelium. Canals and ciliated Chambers are frequent in them, as 

 well as tri- and quadriradiates, the latter lining the cavities in the same 

 way as they, in normal cases do the cloacal tube (fig. 2 PI. 29) . Ac- 

 cording to their morphological value we never see the flagellated 

 Chambers opening directly into them, but by means of the ordinary 

 wide canals, described by me some years ago. 



IV. On the relation between certain Monactinellidae 

 and Ceraospongiae. 



In his paper on the Monactinellids ^ von Lendenfeld states that 

 there is a very close relation between the > echten hornlosen Renieriden« 

 and the so-called Ceraosponges. There cannot be any reasonable doubt 

 that it is true that there are innumerous transitions between both groups. 

 In this point we agree perfectly. But then von Lendenfeld says^: 



1 Zoo). Anzeiger. 1884. No. 164. 



2 1. c. p. 203. 



