1884.] NATURAL SCIENCES OP PHILADELPHIA. 215 



was broken off in some great convulsion of the earth's surface. 

 This had been separated from the main cr3'stal by a piece of 

 orthoclase that had unmistakably been formed since the rupture 

 of the crystal. Such a fact is of great importance in studying 

 the geological history of the formation. The locality is Brudi- 

 nelle, Renfrew Co., Ontario, Canada, and the rock is a vein of 

 pink feldspar in a Laurentian gneiss. It is associated with sphene 

 and crystals of peristerite (?). Some of the faces of the latter 

 show tiie moonstone reflections very plainly. Cavities once filled 

 with calcite (now mostly dissolved away) occur in the vein. 

 There are also some small crystals that need further examination. 



August 19. 

 Mr. J. H. Redfield in the chair. 

 Fifteen persons present. 

 The death of W. L. Schaeffer, a member, was announced. 



August 26. 



Mr, J. H. Redfield in the chair. 



Fourteen persons present. 



The death of James L. Claghorn, a member, was announced. 

 Edward P. Bliss and Ralph W. Seiss, M.D., were elected 

 members. 



September 2. 

 Rev. H. C. McCoOK, D. D., Yice-President, in the chair. 

 Twent3'-one persons present. 



On the wide Distribution of some American Sponges. — Allusion 

 having been made to the wide distribution of certain species of 

 spiders over the North American continent, Mr. E. Potts, refer- 

 ring to the fresh-water sponge fauna of this country, said, that 

 Spongilla fragilis, the first sjtecies named in America, described 

 by Dr. Leidy in 1851 from specimens collected near Philadelphia, 

 bad since been found abundantly along the Atlantic coast from 

 Florida to Nova Scotia. It had been gathered at several points 

 along the St. Lawrence and in the great lakes, through the middle 

 continent, and in the far west had been described by Dr. Bower- 

 bank, in 1863, under the name of S. Lordii, as found in the lakes 

 and streams flowing from the Cascade Range in British Columbia, 



