180 PROCEEDINGS OF THE ACADEMY OF [1887. 



thickly set with spines, which are largest at the middle 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. Amphidisas of 

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

 the surface of the air-chamber-layer. The amphidiscs are thickly 

 set with spines. 



Carter lus stepanowli wtis first discovered in a lake near Charkow 

 in Russia, and was in 1885 found in Bohemia by F. Petr, in a pond 

 near Deutschbrod." 



The above paper of Prof Vejdovsky has been copied in full, as 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. R. 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 o 

 " Potamospongida,'' with a single group, at present named ''Spon- 

 gillinaJ' Hence so far they will stand thus: 



Class SPONGIDA. 



Order VI, HOLORHAPHIDOTA. 



Char. Possessing a skeleton whose fibre is entirely composed 

 of proper spicules, bound together l>y a minimum of sarcode. Form 

 of spicule variable. 



Family 5, POTAMOSPONGIDA. 



Freshwater kSponges. 



Group 19, SPONGILLINA. 



Char. Bearing seed like reproductive organs called stato- 

 blasts." 



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

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



Genera: 1. Sj)oiigUla ; 2. Meyenia ; 8. Heteromeijenia ; 4. Tubelh; 

 5. Parmida; 6. Carterius ; 7, Provisional, (the possible material fof 

 a new group including Uruguaya, Lubo))tir.skia, Potamolepis etc.) 



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

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



