knoion Species o/" Spongilla. 81 



of the animal itself, for whichj in 1872, I proposed the name 

 " spongozoon " (' Annals,' vol. x. p. 45). 



Finally Lieberkiihn, observing what had been pointed out 

 lay Meyen in 1839, viz. that the seed-like body of Spongilla 

 was partly composed of " little toothed" amphidisks, and that 

 besides these there wei'e others with " little points " or spines 

 on their surface (" rauhen etwas gekriimmten "), made these 

 the distinctive characters of Spongilla Jiuviatilis and 8. lacus- 

 tri's respectively (No. 16, pp. 510, 511). This was confirmed 

 by Bowerbank in 1863 (No. 20, p. 7, pi. xxxviii, fig. 1, b,c, 

 and p. 24, tb. fig. 14, c); and good representations of these 

 sponges were given by him in 1870 (No. 25, pis. lix. and Ix.) ; 

 but unfortunately the amphidisk or birotulate is omitted in the 

 former, viz. that illustrating S. Jiuviatilis. Descriptions of the 

 two species, as well as illustrations of the seed-like bodies 

 and their spicules respectively, were also published by Dr. 

 Bowerbank in 1866 (No. 21). 



Thus the two species of Spongilla, hitherto doubtfully 

 distinguished from ignorance of these more decided differences, 

 were firmly established. 



Having premised all the circumstances connected with the 

 history of the freshwater sponge (Spongilla) that are neces- 

 sary for the present occasion, we find that they are quite as 

 much advanced physiologically as those of the marine species ; 

 and although the latter must ever be by far the most numerous, 

 from the great extent of area producing them, yet, when we 

 remember how few known species of Spongilla there are com- 

 pared with the comparatively large area of freshwater which 

 they may be inferred to inhabit, while the localities of the 

 area in which they have been found are, with the exception 

 of Europe, " few and far between," and as yet from Africa 

 none at all have been described, it may also be inferred that 

 hereafter a great many more species will be added to those 

 with which we are at present acquainted, while the latter are 

 already sufficiently numerous and diversified to render a 

 classification of them desirable for further advancement. 



This classification should, of course, be based on some 

 peculiar and persistent characters which may yet admit of 

 modified addition ; and as we have seen that until Meyen 

 had pointed out the form and presence of spicules in the seed- 

 like body, no reliable distinction existed between Spongilla 

 Jiuviatilis and S. laciistris, so we may assume that this may 

 be anticipated throughout the family. And such is the fact ; 

 hence the classification which I am about to propose will be 

 based chiefly on the spicules of the statoblast. 



