1883.} Geology and Paleontology. 967 
server would regard as evidence of a serpentine outcrop another 
would not; but is such explanation, without inspection, scientific ? 
It is certainly not highly complimentary to the gentlemen referred 
to to suggest that they cannot distinguish between mica schist or 
gneiss and serpentine. Will a similar explanation suffice for the 
omission of the very extensive porphyritic gneiss belt in Philadel- 
phia and Lower Merion ? 
To set this question at rest, it is my purpose to exhibit at an 
early fall meeting of the Academy of Natural Sciences a suite of 
specimens from these outcrops, that those interested may see for 
themselves. 
If it is seriously urged that a continuous valley clearly syncli- 
nal at each end is monoclinal in the middle of its length, it may 
not be so very unwise or unfortunate, as Mr. Hall asserts, to en- 
deavor in that “middle to unravel a snarl in the tangled skein.” 
In defence of the Mineralogical and Geological Section, if de- 
fence be needed, I would only say that had all its other founders 
and members contributed as extensively to it as has its critic 
there would have been nothing to criticise.— Theo. D. Rand, 
hila., June 20, 1882. 
HULKE ON ICHTHYOSAURUS AND PLEsIOSAURUS.—In the course 
the radius and ulna (epipodial) in Plesiosaurus to a mesopo 
(tarsal or carpal) position in Ichthyosaurus. 
