Dr. J. E. Gray on the Glasslfication of Sponges. 459 



Order VI. SPHiEROSPONGIA. 



Sponge generally massive, gruraose ; skeleton strengthened 

 with numerous small spicules crowded into globular or stellate 

 balls, and with elongate spicules terminating at the outer end 

 in three recurved spines, which are simple or forked. 



I. The globular or ohlong halls of spicules crowded^ forming a 

 coat to the outer surface of the sponge. 



Bowerbank regarded these balls of spicules as ovaria. I 

 have called them in my arrangement of sponges ovisacs ; but 

 further research has convinced me that they have nothing to 

 do with the ova. 



A. Sponge grumose^ with elongate spicules, the long ones with 



two or three expanded or recurved acute branches. 



Fam. 1. GeodiadsB. 



The spherical masses of spicules forming a thick external 

 crust to the sponge. 



a. Crust interrupted with a conical cloaca covered with a 

 netted or perforated lid. Oeodia. 



h. The external crust continuous. Cydonium and Pachy- 

 mo.tisma. 



B. Sponge calcareous, solid, with simple spicules between the 



outer layer and axis, which is formed of spheres of sjn- 

 cules. 



Fam. 2. Placospongiadae. 



Sponge branched, coral-like, with a central axis and a hard 

 outer coat entirely formed of solidified spherules of spicules. 

 The axis and outer lamina separated from each other by a 

 layer of sarcode strengthened with bundles of spicules. 



Placospongia. 



II. Tlie stellate halls of spicules scattered in the outer surface 

 and inner part of the sarcode. 



Tethyad^, Gray, P. Z. S. 1867, p. 540. 



Sponge oblong, massive, fleshy, armed with simple fusiform 

 spicules, many having three prongs or three recurved points 

 at the outer end or distal outward extremity, forming the 

 surface or extending beyond the surface of the sponge, and 



31* 



