174 PROCEEDINGS OF THE ACADEMY OF [1887. 



bound into fascicles, which are either long threads, or are placed as 

 a network in the tissues. Hooked spicules cover the gemmulse and 

 are widely dispersed through the tissues. They live in ponds and 

 quiet flowing water and appear to be the most widely distributed spe- 

 cies of Germany." 



Although from this description of Retzer's it is evident that Spov- 

 gilla lieberkuhnii only slightly differs from his S. lacustrls, I thought 

 it necessary to examine for myself the nature of the form in question. 

 From a small fragment of S. lieberkuhnii for which I must thank 

 Prof. Eimer, I clearly recognize its identity with iS. lacustris. In 

 the form of tlie gemmulse and the scarcity of the covering spicules 

 I find no difference between them ; sections of the gemmulje prove 

 that the air-chambei'-layer is more or less developed and its surface 

 may be with or without a liorny membrane ; which is also the case 

 with E\ispon(iiUa lacustris in various localities in Bohemia. 



The immense, even predominating quantity of the strong, rough 

 parenchyma spicules, and an equally large number and variety of 

 the external form of the gemmulae spicules these are, on the other 

 hand, the striking characteristics wliich strongly suggested the re- 

 cognition of a similar form from the Jordan Pond, near Tabor, in 

 Bohemia, as a distinct species, {Eui^poiu/illa jordanensi^). But the 

 quantity of sponge material that has been at my disposal for some 

 years, convinced me otherwise. In some specimens from the Elb, 

 near Koniggriitz and from a pond near Poiakek (?) I found the 

 gemmulse and covering spicules to correspond with each other, and 

 with the characteristic type of 8. lacustris ; while in single branches, 

 they were identical with the same features in E. jordanensis>, from 

 the Jordan Pond ; and at the same time a corresjionding quantity 

 of rough parencliyma spicules was found in its tissues. We must 

 therefore unite E. jordanemis with E. lacustris. 



E. lacustris, var. macrotheca, very neax'ly resembles tlic following 

 species. 



(2) Euspoagilla rhenana, Kci/.cr. 



Syn. 1883 Sponcjilla rhenana, Retzer. 

 This interesting species was first described by Retzer in the fol- 

 lowing terms: "It differs from tlie other species by the smooth gem- 

 mula; spicules." 



"It encrusts pieces of wood, buslies and the like, sending out a 

 few small processes ; and also in many places forms thick masses. 

 The skeleton spicules are straight or slightly curved, abruptly or 



