ON MEKLIA NORMAXI. 681 



.(f) Clioanocy tes. 

 (See nncler "Canal System," Section 1, and PI. 33, figs. 8-12.) 



(g) Calcigenous Aiiiffibocytes or Calcocytes. 



It is to these cells tliat the extraordinary character of 

 Merlia is due. for they are calcigenous, and it is their 

 function to build the calcareous skeleton. 



Quite apart from their lime-forming function, the an auge- 

 ment of these masses of cells in the form of moniliform 

 cylinders is a very remarkable feature. 



Befoi-e I had understood the structure of Merlia I called 

 these cells crypt-cells, because many of them are found in 

 spaces of the calcareous skeleton covered over b}- tabular. 

 As I am now practically certain tiiat these cells which fill up 

 tlie crypts also build those structures, I suggest the designa- 

 tion "calcocyte," which is in keeping with the cytological 

 terms now in use. Since these lime-torming cells of a sili- 

 ceous sponge constitute a special and unique phenomena, ] 

 think they should be distinguished by a separate name from 

 the telmatoblasts, or better, telmatocytes, which form the 

 cement in Pharetron sponges. (8) 



The lime-forming cells of Merlia are exceptionally de- 

 serving of the designation " anicebocyte," for they exhibit 

 a remarkable variation in shape in accordance with their 

 position in the sponge and the kind of work they have to do. 

 Before setthno- down to build the skeleton and. in places 

 where they are not compressed in an enclosed space they are 

 more or less elongated (PI. 38, fig. 1). When caught in the 

 isthmus between two crypts they may be vermiform (PI. 36,. 

 fig. 3, and Text-fig. 2). In the crypts, where the cells are 

 pressed against each other, they are massive and cylindrical 

 or pyriform (PI. 36, figs. 1-4), excepting on the outer surface 

 of the crypt masses, in which situation they become flattened 

 (PI. 34, fig. Qa, and Text-fig. 5) . When form ing the bars of the 

 young calcareous skeleton or the inner smooth walls of crypts 



