180 PROCEEDINGS OF THE ACADEMY OF [188T„ 



thickly set with spines, which are hir^est at the iniddle of the spic- 

 ules. Gemmulse marked by a polar air tube which is straight or 

 slightly bent, and terminated by a wavy, lobulated disc. The air- 

 chamber-layer is formed of numerous small cells. Amphidiscw of 

 two lengths, of which one third or even a half may project beyond 

 the surface of the aii--chaniber-layer. The amphidiscs are thickly 

 set with spines. 



Car-terius stepanoivii was first discovered in a lake near Charkow 

 in Russia, and was in 1885 found in Bohemia ])y F. Petr, in a pond 

 near Deutschbrod." 



The above paper of Prof. Vejdovsky hiis been copied in full, ti.s a. 

 very valuable statement of the present status of the specific study 

 of fresh water sponges in Europe, more particularly upon the con- 

 tinent. 



Synopsis. 



Of the plan of Classification proposed by H. J. Carter, F. K. S. 

 etc., (Ann. and Mag., Feb. 1881) already referred to, he says: — " I 

 found it necessary to make the fresh water sponges the fifth family 

 of my sixth order of the Sponglda generally, under the name of 

 ^'Potamospongida,'' \iii\\ a single group, at present named "Spon- 

 gil/ina." Hence so far they will stand thus: — 



Class SPONGIDA. 



Order VI, HOLORHAPHIDOTA. 



C/iar. Possessing a skeleton whot-e fibre is entirely compose* i 

 of proper spicules, bound together by a minimum of sarcode. Form 

 of spicule variable. 



Family 5, POTAMOSPONGIDA. 



Freshwater Sponges. 



Group 19, SPONGILLINA. 



Char. Bearing seed like reproductive organs called stato- 

 blasts." 



To the five genera nanieil by him, two have been added, to define 

 some recently discovered American types, so that the list now stands. 



Genera: — 1. Spongilla ; 2. Meyenia ; 3. Heteromeyeuia ; 4. Tubella; 

 5. ParmiUa; (>. Cartei'lus ; 7, Proimlorud, (the possible material for 

 a new group including Uruguaya, Lubomirskia, Potavio/epis etc.) 



As has been intimated, these genera have been founded upon the 

 peculiarities of the geniniule-spicules, except in one instance, which 



