122 JOURNAL OF THE [May, 



to the group Clionidae. Fastening itself to the shell of the 

 oyster, this sponge eats into it, tunnels it, and sometimes pierces 

 even the inner nacreous layer. The peculiar construction of 

 the shell facilitates this work. The shell is made up of a suc- 

 cession of calcareous plates, which are more or less discontin- 

 uous, and are of increasing size as they recede from the umbo. 

 These layers are hard, and strongly resist the saw. Between 

 them is a soft packing, consisting of prismatic calcareous 

 material, which cuts as easily as cheese. When, therefore, the 

 sponge has bored through a hard plate of the shell, it spreads its 

 branches readily through the soft material beneath. It is ob- 

 vious that, especially where the packing between the hard layers 

 has been rendered continuous because of a want of continuity 

 in those layers, the work of destruction must be rapid, and that 

 the shell will soon become disintegrated. I have seen oyster- 

 shells which had become so thoroughly perforated by the boring- 

 sponge that the two valves, when pried open by the knife, fell in 

 pieces, leaving only two small plates where the adductor muscle 

 was attached. 



PROCEEDINGS. 

 Meeting of April 3D, 1885. 



Tlie President, Mr. C. Van Brunt, in the chair. 

 Thirty-three persons present. 



OBJECTS EXHIBITED. 



1. Fourteen Photographs of Diatoms; taken in 1876, by J. J. 

 Woodward, Asst. Surg., U. S. A.: by A. Woodward. 



2. Eighty-eight Diatoms, arranged in three rows ; mounted by 

 Mr. Peticolas : by C. S. Shultz. 



3. Fifteen Diatoms, arranged in a star-shaped group : by C. 

 S. Shultz. 



4. Diatoms from Puget Sound : by C. S. Shultz. 



5. Diatoms from Ajaccio, Corsica : by C. S. Shultz. 



6. Five Slides of miscellaneous Diatoms : by C. S. Shultz. 



7. Conochilus volvox, and Volvox globator : by A. D. Balen. 



8. Iridescent shell of Baculite ; from Dakota : by G. F. Kunz. 



9. Ruby Copper, from Cornwall, England : by G. F. Kunz. 



