176 PROCEEDINGS OF THE ACADEMY OF [1881. 



July 19. 



The President, Dr. Ruschenberger, in the chair. 



Twelve persons present. 



A paper entitled " A Revision of the Cis-Mississippi Tertiary 

 Pectens of the United States," by Angelo Heilprin, was pre- 

 sented for publication. 



July 26. 

 The President, Dr. Ruschenberger, in the chair. 

 Twelve persons present. 



A New Form of Fresh-ivater Sponge. — A note was read from 

 Mr. Edw. Potts, reporting the discovery in Chester Creek of 

 another curious form of fresh-water sponge, a third species of 

 Carterella, resembling C. titbisperma in the character of its 

 birotulates and the length of its foraminal tubes, but much more 

 robust than that species. The tendrils are nearly as long as those 

 of C. tenosperyna, but broad, flat and ribband-like. 



Thus far it is the most conspicuous and peculiar of our Ameri- 

 can forms. He proposed for it the name Carte7'ella latitenta. 



John Gr. Graham was elected a member. 

 The following was ordered to be printed : 



