282 Mr. H. J. Carter on 



Liverpool, close to the entrance of a freshwater tributary, the 

 only difference that I can see, for I have specimens of both in 

 my possession, amounts to the simple modification that arises 

 from a predominance of keratine, whereby the open-sea speci- 

 men is tougher and more resilient than the estuary one, which, 

 being the reverse, is softer and more fragile, the spicules 

 being much the same in size and shape in both. 



How far the general form and the sausage-shaped spicule 

 of the freshwater sponge JJruguaya corallioides, Bk., which 

 equally agrees in these respects with both Ghalina japonica 

 and Chalina mauritiana, may favour the view of those who 

 would refer JJruguaya to a marine origin, I am not able to say ; 

 or to come to the conclusion of Dr. W. Dybowski that, because 

 Luhomirskia haicalensis, viz. the solid, caulescent, branched, 

 chaliniform freshwater sponge of Lake Baikal, in Central 

 Asia, is identical in general structure and in the form and 

 nature of its spicule with a similar but marine one which his 

 brother sent him from the shores of Behring's Island, in the 

 Xamtschatka Sea, — the former is necessarily the latter living 

 in fresh water (" Die Behringsschwamrae weichen weder in 

 ihrer Struktur noch in der Gestalt und BeschafFenheit der 

 Spiculen von denen der Baikalschen Exemplare ab, so dass alle 

 diese, obgleich aus so sehr verschiedenen Fundorten herkom- 

 menden Schwamme, als vollkommen identisch anzusehen 

 sind," Sitzungsbericht d. Dorpater Naturforscher-Gesell- 

 schaft, Jahrg. 1884, p. 45), although geologically considered 

 it is as easy to infer that the sea, when receding from the 

 interior of continents, might have left saltwater lakes there, 

 which have become as fresh as the marine formations beside 

 them, in which there is now not a particle of salt left. But 

 as yet, if neither JJruguaya nor Luhomirskia haicalensis has 

 been found to possess statoblasts, so neither have they been 

 found in an ovigerous condition — conditions, especially of 

 the latter, which can only be maintained for home-demonstra- 

 tion by being at once preserved in some aqueous medium, 

 such as spirit and water ; i. e. on the spot. 



I have entered more at length into this subject here than 

 I had an opportunity of doing in my report on the Japan 

 sponges, chiefly because the Mauritius sponge is, according 

 to my view, a Chalina {C. mauritiana), and its spiculation 

 so peculiar that it is deserving of special mention. 



Lastly, for my observations on the fourth or concluding 

 family of the order Rhaphidonema, viz. the Pseudochalinida, 

 I must refer the reader to the species described in the ' Annals ' 

 of 1882 (vol. ix. p. 280), and 1885 (vol. xv. p. 319). 



