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rest of the cortex, we find in Geodia that the cloacal skeleton 

 is different from the cortical skeleton. The details I hope to pu- 

 blish later, when I can give full illustrations ; at that time I will 

 treat also more in extenso the views of other authors. 



A complicatiou of the ultimate exhalant openings we find in 

 several sponges, e. g. in Cydonium gigas (O. S.). Here we see that the 

 excurrent chones do not open simply with oue mouth (proct), but 

 that a thin membrane with a special skeleton and perforated by 

 numerous small openings covers it. I call these openings proctions; 

 a system of proctions belonging to one excurrent chone thus cor- 

 responds with one proct. 



In the same Cydonium gigas we find that the inhalant chones 

 resemble exactly the exhalant ones, and that a nuraber of inha- 

 lant apertures lie together in a membrane (dermal membrane) 

 over one chone. Sections through the cortex of Cydonium show 

 that under that dermal membrane a system of holes occurs, which 

 cavities are thus undoubted subdermal cavities, and esseutially 

 distinguished from the series of cavities under the cortex , the 

 so-called crypts. The very wide beginning of the inhalant chone 

 is therefore equal to a subdermal cavity. The small apertures in 

 the dermal membrane of Cydonium I propose to call stomions. In 

 other Geodidae we see that each chone begins with one single 

 opening. If we assume all the chones of the Geodidae homolo- 

 gous, then a group of stomions corresponds to one stoma, as I 

 will call those single inhalant apertures. 



In this short note I will not discuss what in other sponges 

 may be called stoma or stomion. This however I hope soon to 

 do in another paper. 



