176 B. W. PRIEST ON THE STATOBLASTS OF 



hedral cells, hexagonal as seen in section or when focussing for the 

 surface, regularly arranged one above another in juxtaposition, per- 

 pendicularly to the outside of the chitinous coat. 



This species has only been found as yet in India, Mauritius, and 

 lately by Dr. Margo'of Budapest, in Europe, in the Lake of Balaton. 

 My own specimen, for which I am indebted to Dr. Matthews, comes 

 from Jheels, opposite Benares. 



The only British species of this genus is Spongilla lacustris, the 

 Statoblasts of which have the spicules more or less curved, minute, 

 stout and sharp-pointed. They are covered with stout recurved 

 spines, the outer crust being composed of micro-cellular structure. 



This species is found growing somewhat plentifully up the Thames, 

 at Henley, Goring, and Marlow, and is also met with in Europe 

 generally, North America, and Asia, but the finest specimens that 

 I have seen have come from the Upper Thames. 



The remaining eight species of this genus are S. alba, S. pau- 

 perenta, S. cinerea, S. cerebellata, S. nauicella, S. multiforis, (so 

 named on account of having several openings to the Statoblast, 

 this species is also apparently devoid of a crust), S. Lordii 

 and S. nitens. This last-named species has the pyramidal columns 

 in the outer crust, like S. Carted, all other species having the 

 granular or micro-cellular structure. 



The next genus is Meyenia, after Meyen, who first discovered the 

 presence of bi-rotulate spicules characteristic of this genus, and it 

 comprises eight species. The Statoblasts are globular or oval, the 

 micro-cellular structure of the crust being charged with bi-rotulate 

 spicules, that is spicules which consist of a straight shaft terminated 

 at each end by a disk, even or denticulated at the margin, arranged 

 perpendicularly around the chitinous coat, so that one disk is 

 applied to the latter, while the other forms part of the surface of the 

 Statoblast. 



In Meyenia fiuviatilis (Spongilla fiiiviatilis of Bowerbank) the 

 species most generally known, and in which many varieties occur, 

 as instanced in Mr. Waller's paper on that subject,* the umbonate 

 disks are deeply and irregularly denticulated, and the shafts in 

 some cases more or less spiniferous. The Bombay species, S. 

 Meyeni, and the River Exe species, S. Parfittii, have both kinds 

 of spicules, viz., smooth and spined, proving that they are only 

 varieties of M. fiuviatilis. 



* '< Q. M. J.," Vol. v, p. 53. 



