268 PROCEEDINGS OF THE ACADEMY OF [1887. 



We have now examined in detail all the genera comprised in the 

 group SpongiU'ma, that are clearly characterized by the presence of 

 "seed-like reproductive organs called statoblasts" or gemmules. There 

 yet remain three genera in which no such organs have been discovered. 

 As shown by their geographical derivation, they are as certainly 

 fresh water sponges as any of the others, and the absence of the sup- 

 posed distinctive features, may or may not prove to be real. They 

 have not yet been found; that is all. But neither have the sponges 

 been examined at the place of their growth, if we except the L%ibo- 

 mirskice, by any one familiar with the peculiarities of the fresh water 

 forms, who has torn to pieces mass after mass, as was done in the case 

 of S. lacustrls, v. abortiva, S. aspinosa, H. pictovensis etc; as must be 

 done in our treatment of all the evergreen sponges, which, probably 

 for the very reason that they live throughout the year, perfect but 

 few gemmules. 



I know that it is in the line of my own arguments, already given, 

 to believe it possible that fresh water sponges, living in deep, 

 tropical waters, should not adopt this method of reproduction ; and 

 I do believe it, theoretically. It is necessary however that this theory 

 should be proved by a more thorough and systematic examination, 

 of the genera now to be briefly mentioned, which are neither all 

 tropical nor "deep" in their origin, when, if they maintain their 

 claim, it will be in order to form a new group to comprise them. 



Between two of these genera there is a strong family resemblance 

 at least in the forms of their skeleton spicules. Those of the third 

 genus, Luboviirskia, as well as the prevailing habit of the species, seem 

 to differ from the others. I regret that I have not been able to find 

 English translations of Dr. Dybowski's descriptions, but can present 

 only the meagre sketches prepared by H. J. Carter from his exam- 

 ination of the plates furnished by the author. 



(Vila.) Prov. Gen. UKUGUAYA, Carter. 

 TJruguaya corallioides. Carter. Ann. and Mag. 1S81, p. 100. 



Spongilla corallioides, Bowerbank. Proc. Zool. Soc. etc. 1863, p. 



460. 



Sponge "irregularly digitate ; rising into a polychotomous and 

 anastomosing mass of cylindrical branches, which may attain sever- 

 al inches (seven or more) in all directions. Color faint whitish yel- 

 low or dark leaden on the surfjice ; internally white or colorless. 



Surface even, vitreous in appearance, extremely hard, smooth and 

 compact, interrupted by small raised vents, more or less uniformly 



