433 PROCEEDINGS OF THE ACADEMY OF [1890. 



not regular, while the garnetiferous schists dip less steeply and in- 

 variably to the southeast. The garnets are frequently absent over 

 large areas ; again they are abundant, but as a rule less so as we 

 a{)proach the hydromica. On the East Branch of the Brandywine, 

 atid on the adjacent affluent, Valley Creek, the mica schists appear 

 to be between two and three miles wide, while the hydromica nar- 

 rows to probably less than three quarters of a mile. 



This is in marked contrast to the exposure in Radnor, twelve 

 miles to the northeast, wiiere the mica schists are not over 200' wide 

 while the hydromicas extend two miles. On the East Branch the 

 contact is near Hawley's Mill. The actual contact cannot be ob- 

 served but the change of dip and in the character of the rock is well 

 marked. 



In these schists northwest of West Chester near Taylor's Mill, 

 fragments, apparently of Potsdam sandstone, were found similar to 

 the occurrence in Cream Valley and in them or next to them also 

 occurs the limestone of this region. 



In the discussions of the geology of this section it seems to have 

 been taken for granted that the topographical South Valley Hill 

 was wholly of hydromica schists which widened westward. The 

 fact that the mica schists in question are not of the same age as the 

 hydromica schists may explain in part the want of agreement be- 

 tween different geologists on this region. It was his intention to 

 study this farther and present the facts more fully hereafter. 



December 9. 

 Dr. Geo. H. Horn in the chair. 

 Thirty persons present. 



December 16. 

 Dr. Benjamin Sharp in the chair. 

 Thirty-seven persons present. 



Trichia proximella Karst. — Dr. Geo. A. Rex presented spec- 

 imens of Trlchia j)i-oximella Karst. and described its specific char- 

 acters, history, and geographical distribution. 



This species is not rare in the United States, having been found 

 in many localities, its range, as far as yet known, extending from 

 Canada to North Carolina and as far west as Iowa. 



It occurs, however, less frequently than Trichia ckrysosperma 

 Rost. growing usually in small, scattered clusters of minute, closely 

 aggregated, sessile sporangia of a golden brown color. 



In the Journal of Mycology for August, 1886, the speaker had 

 published a paper giving an analysis of the results of an examination 



