134 The American Geologist* August, 1894 
pear to be two species: one of them is probably C. pleurexant hemus\ the 
other species, which remains undetermined, is smaller and less abun- 
dant. It is nol certain to which <>f i hese species the caudal spines found 
associated with them should be referred. 
There are I wo other trilobites: one is a small species, apparent ly a Dul- 
iiitniiii. of which tin' pygidium alone is round: and the other is supposed 
to be a species of Enerinurus, also in fragments. Another form differs 
from anv described in the Wisconsin reports, being less rotund and 
showing the three lobes by slight depressions in the smooth surfai f 
the pygidium. The outline is parabolic. The axial or medial lobe is 
fully one-third of the breadth, anteriorly, hut it tapers rapidly posteri- 
orly, with t he sides incurved. This axial lobe is only slightly convex, 
hut the lateral lobes slope downward steeply toward the margin, thus 
presenting an outline in cross-section very different from any figured in 
the Wisconsin reports. Possibly these should be referred to Asaphus. 
The form of some of the fragments of the cephalic shield favors this 
view. 
Amongst the other associated fossils in a good state of preservation are 
two or three species of Qrthis and Murchisonia; one of Orthoceras; Oypri- 
eardites, Raphistoma, Byolithes, Streptelasma, and encrinal stems. These 
may not all be from one stratum, but they are thrown out from lint 
same mine and are at least in neighboring layers and contiguous to a 
deposit of galena in a layer with calcite in a blue clay. The horizon of 
all the fossils is the "oil -rock" or bituminous shale series of thinly bed- 
ded limestones, at the top of the Blue limestone of the Trenton and at 
the base of the Galena dolomite. 
1 have not been able to find any traces of antennae in connection with 
tlie trilobites. There are many obtuse conical fragments, beautifully 
facetted, supposed lo be the eyes of the species here referred provision- 
ally to Ertcrinurv.8 or Asapkus, supported on gracefully shaped peduncles 
rising from the smooth surface of thin plates. 
The specimens 1 have collected need examination by competent au- 
thority, and it will give me pleasure to submit the collection to any 
specialist who will undertake to describe the species for publication. 
Wm. P. Blake. 
Helena Mill, Shullsburg township, Wisconsin, -him ?0, 1894. 
The Rock Basin op Cayuga lake. A paper on this subject bj 
Prof. R. S. Tai-r, was read before the Geological Society last December. 
and is published in I he Bulletin of the Society. As it touches upon my 
investigations, 1 have a word or two of comment at present. He bases 
his conclusions on certain lateral phenomena, and compares the former 
slope of the drainage with the present lake Level. In this paper he says 
that the greatest depth of the lake' is 135 feet, being near the southern 
end. Now. Mr. McGee has shown that the late terrestrial deformation 
along the upper Susquehanna river is three feet to t he mile to the north. 
1 have shown the same to occur in the Niagara district, and Mr. Gilberl 
and myself have shown this or greater amounts at the eastern end of 
