1894.] _ Zoology. 347 
the supposition that the ganoid scale is a number lof placoid scales 
used together. There can be no homology between them except in 
their both being dermal struciures. In the Selachians the basal plate 
originated in connection with the formation of spines, but in the 
Lepidosteus the spines have degenerated while the basal plate has devel- 
oped independently at the same time sinking deeper in the dermis. 
In the Telosts there is no ganoine, but a modification of the dermis 
takes place similar to that in Lepidosteus. The same sinking or a ten- 
dency to reduction of superficial parts and increase of the deeper 
parts, involving the reduction of spines. In the lower Teleosts the spines 
are connected with the scale by connection tissue only, thus showing a 
more degenerate condition than in Lepidosteus. 
It appears, then, that the Lepidosteus and Teleost scales have 
been derived from the placoid scale along independent lines——F. C. 
KENYAN. 
Mammalia of Mt. Pocono.—Considering the fact that hitherto 
no systematic collecting of small mammals has been attempted in the 
Pennsylvania mountain districts the following notes may seem worthy 
of record. During the latter part of June and first week of July, 
1893, in company with Mr. Witmer Stone, I spent about ten days col- 
lecting birds and mammals in the vicinity of Mt. Pocono, Monroe Co., 
Penna. The general situation and elevation of the locality warranted 
a much more northern fauna than that found in the southeastern part 
of the state, and it is hence not at all surprising that such boreal forms 
as Zapus insignis, Evotomys gapperi and Tamias striatus lysteri were 
obtained. None of these, so far as I am aware, have been previously 
recorded from Pennsylvania. 
A list of the mammals collected is as follows: 
Blarina brevicauda.—This shrew was the most abundant of any: spe- 
cies noted; the specimens secured forming over 30 per cent of the 
whole number collected. I found them, as Dr. Merriam has said, 
moving about during the day, and on my afternoon visit to the traps 
rarely failed to secure one or more. Several were taken in the same 
runs with E. gapperi. 
Sorex platyrhinus (Dobson).—T wo specimens of a small shrew were 
secured which Mr. G. S. Miller, Jr. has kindly referred for me to this 
species, using the name as a provisional designation. A third speci- 
men, badly decomposed, was found in the middle of a road through 
the woods. Of this the skull only was preserved 
Evotomys gapperi—Five specimens of the red-backed mouse were 
