THE FRESHWATER SPONGES. 177 



Iii Meyenia phtmosa (perhaps the most beautiful of any of the 

 freshwater Sponges as a microscopical object), the Statoblasts are 

 oval-, with the aperture lateral, the umbonate disk is of equal size 

 and the margin is irregularly denticulated, with the processes more 

 or less turned inwards. The shaft is long, straight, and sparsely 

 spiniferous, the spines being large, conical, and perpendicular on 

 their surface. I may mention here, that it is the only species of 

 freshwater Sponge that has the flesh spicule stelliform, consisting 

 of a number of arms of various lengths radiating from a smooth, 

 globular body, the arms spined throughout. This species comes from 

 Bombay. 



The remaining six species are, M. erinaceus, AI. Leidii, M. gre- 

 garia, M. Capeivelli, M. Baileyi, and M, anonyma. 



We now come to the genus Tubella, signifying a little straight 

 trumpet, so named on account of the spicules, charging the crust of 

 the Statoblast, having the shaft passing by a trumpet-like expansion 

 into a disk at one end, this disk being larger than the other. 



The Statoblast of this genus is either globular or elliptical, the 

 aperture lateral or terminal. It comprises four species, Tubella 

 reticulata, T. paalata, T. spinata, and T. recurvata. The typical 

 species, T. reticulata, has the Statoblast elliptical, ovoid, aperture 

 terminal, crust composed of micro-cellular substance, charged with 

 inecjiii-birotulate spicules, consisting of a straight shaft passing by a 

 trumpet-like expansion into the larger disk, with two or more spines 

 about the centre, and furnished with a ring-like inflation towards 

 the disk; which disk is circular, smooth, with an even margin, some- 

 what recurved, the opposite end of the spicule consisting of a cir- 

 cular umbonate head, regularly denticulated on the margin with six 

 or eight conical processes. The spicules are arranged perpen- 

 dicularly, so that the small end forms part of the surface of the 

 Statoblast, whilst the disk rests on the chitinous coat. It is in 

 this genus that the Statoblasts seem to have been developed in a 

 capsular covering composed of spicules similar to those forming the 

 skeleton of the sponge, which are bent, subfusiform, and rounded 

 at the ends, only half the size and more thickly spined. This 

 species comes from the River Amazon. 



The remaining genus of which we know anything of the Stato- 

 blast, is named Parmula, a little round shield, on account of the 

 form of some of the spicules. There are two species, P. Batesii 

 and P, Brownii. 



