1881.] NATURAL SCIENCES OP PHILADELPHIA. 149 



June 14. 

 The President, Dr. Ruschenberger, in the chair. 

 Twenty-one persons present. 



A paper entited " Notes on the Tertiary Geology of the South- 

 ern United States," by Angelo Heilprin, was presented for pub- 

 lication. 



The death of Baron Maximilien de Chaudoir, a correspondent, 

 was announced. 



Some new Genera of Fresh Water Sponges — Mr. E. Potts re- 

 ferred to a recent paper by H. J. Carter, F. R. S., (Ann. Mag. 

 Nat. Hist., Feb. 1881,) entitled, " The History and Classification 

 of the Known Species of SjMngilla,^^ in which the writer has dis- 

 tributed the species, heretofore grouped under one generic title, 

 among five genera, founded upon the differences in form and ar- 

 rangement of the spiculse surrounding the statospheres. He 

 spoke of the arrangement as a timely step well taken in ad- 

 vance, in the history of this branch of the animal kingdom. 



He believed that the characteristics of the statospheres and 

 their spiculaB were those which furnished the only reliable dis- 

 tinctions among fresli water sponges ; but the recent discovery of 

 novel forms in American waters had already required an increase 

 in the number of genera and seemed to make it desirable to 

 modif}^ the terms of some of those already established. 



In illustration he referred to several forms observed in this 

 neighborhood, resembling in many points the English Spongilla 

 lacustris, (taken as a type of the genus Spongilla in the new ar- 

 rangement), in which, however, the spiculae were not acerate, but 

 irregular in shape ; were not placed " tangentially " upon the 

 surface ; or were altogether wanting. Specific names were suggested 

 for these, but were held under ad\'isenient, awaiting a decision as 

 to whether it would be better to create new genera for them or to 

 enlarge the scope of those alread}^ defined b^^ Dr. Carter. 



The two new genera already decided upon were then described. 

 Under the generic head Ileyenia, Dr. Carter has grouped those 

 species, in which the statosphere is surrounded b}^ birotulate 

 spiculae, radiateh' arranged ; one disk resting upon the surface. 

 Throughout the genus as alread^y constituted, the shafts of these 

 spicules are of a nearly uniform length ; and the outer disks nearly 

 or quite touching at their edges give the appearance of a second 

 coat to the statosphere. In two species, however, observed 

 by Mr. Potts last summer, this uniform series was broken by 

 another, of about double their length, much fewer in number, 

 somewhat regularly arranged, interspersed among them. He 



