164 ANATOMY AND PHYSIOLOGY 



Leucosolenia, Bowerbanh. 



GsANTU, Fleming and Johnston. 



Sponge. Fistular. Formed of a single layer of triradiate 

 and other spicula, surrounding a large central cloaca, 

 which extends into all parts of the sponge. 



Tjrpe, Grantia botryoides, Fleming. 



The structure of Grantia botryoides, Fleming, differs 

 essentially from that of Grantia compressa of that author, 

 inasmuch as there is a total absence of the interstitial 

 cells which are so characteristic of the latter sponge ; and 

 its structure is equally discrepant when compared with 

 that of Grantia nivea of Fleming ; for although it possesses 

 cloacae in common with that species, it has no approxima- 

 tion whatever to the massive Halichondroid form of the 

 substance of that sponge. On the contrary, its parietes 

 consist of a single thin layer of spicula and membranous 

 tissues surrounding a large central sinuous cloaca. Figs. 

 347, 348, Plate XXVL 



Leuconia, Grant. 



Gbastia, Fleming and Johnston. 



Sponge. Furnished with cloacae, one or more. Parietes 

 of sponge formed of a mass of irregularly disposed 

 interstitial membranes, and triradiate and other spi- 

 cula ; permeated by sinuous excurrent canals, the 

 oscula of which are irregularly disposed over the 

 surfaces of the cloacae. 



Type, Grantia nivea, Fleming. 



Grantia nivea of Dr. Fleming is very different in its 

 structure from either G. compressa or ciliata, or of G. 

 botryoides of that author. It has not the regular inter- 



