244 PROCEEDINGS OF THE ACADEiMY OF [1883. 



Hill into Delaware county, terminating near the road leading 

 from the Lancaster turnpike to the King of Prussia. 



In fact, it is nowhere near the summit, but on the south flank, 

 or at the foot, and so far from ending at the road mentioned, it 

 extends several miles to the westward, its outcrops almost con- 

 tinuous. 



7. P. 140: "Near Mr. Hitner's house, Marble Hall, there 

 occurs a thin bed of very ponderous rock, resembling closely a 

 white crystalline limestone. It contains, however, but a moderate 

 proportion of carbonate of lime, and consists chiefly of the car- 

 bonate of strontia." Whence there is deduced a bond of connec- 

 tion between the valley limestone and the No. 11 limestone of the 

 valleys of middle Penns3dvania. 



Was carbonate of strontia ever found there ? Is it not the 

 well-known sulphate of baryta from that locality mistaken for 

 carbonate of strontia ? 



8. P. 282 : "An old quarry close by the Spread Eagle hotel, 

 which is now filled with fragments of trap and rubbish, shows 

 serpentine along with the schistose matter, with a dip about 

 S. 35 E., and seemingly about 35°, etc." 



" This quarry is over the line, in Delaware county." 

 This is an interesting contact. I regret that I have been unable 

 to find it ; the onl}^ quarry in that vicinity that I can find is about 

 200 feet west of the Spread Eagle, on the north side of the Lan- 

 caster turnpike, nearly opposite Pugh's store ; but it contains no 

 serpentine, and is in Rogers' altered primal quarried thence for 

 the turnpike. It was much filled up with trap and rubbish, but 

 has been recentlj^ opened again. Old residents assure me that it 

 is the only quarry in Delaware countj' in that vichiity. 



9. P. 282: "As soon as one passes the creek north of Radnor 

 station * * * ^\iq measures assume an unctuous, schistose, 

 partly chloritic character," 



P. 284 : " Fragments of chloritic mica schist." 



P. 28Y : " Willistown, broad conchoidal mica schist, containing 

 much chlorite and milk quartz." 



Yet Prof. Frazer contends rightly (Am. Nat., October, 1883, 

 p. 1021) that this region contains hydro-mica schists only; that 

 the expression " talc mica " is erroneous, as the rocks contain no 

 talc ; do they contain chlorite ? 



Dr. Frazer says (Am. Nat., May, 1883, p. 524) : " The observa- 

 tion of the intersection of the serpentine belt by the trap, which 



