1890.] NATURAL SCIENCES OF PHILADELPHIA. 123 



Except the Conslioliocken trap dyke, aud the numerous dykes of 

 the Laurentian, mostly small and apparently of limited length, 

 I have nowhere found trap in the region. I have visited the 

 localities at which the trap is shown on the map in Vol. C* except 

 Howellville, Delaware county, which is in Laurentian, and I believe 

 that on Chester creek and also on Colleen brook near Darby creek a 

 very compact gneiss has been taken for trap. 



In the schists and gneisses east of the porphyritic and especially in 

 the Fairmount gneiss the granite is usually segregated, but it is prob- 

 able that intrusive masses occur. ^ 



1 2nd. Geol. Survey of Pa. Ann. Rep. 1886, IV, 1602, & plate 1570. 



