LOWER CRETACEOUS ROCKS OF BRITISH COLUMBIA. 85 
species, collected by Dr. Dawson, has convinced the writer that the Aucella Piochii of Gabb 
cannot be distinguished from the A. Mosquensis of Von Buch, even as a local variety. In 
the neighborhood of Moscow the latter species, according to Eichwald, forms great banks 
of shells, just as its American representative appears to do in certain localities in British 
Columbia. Aucella Mosquensis has been recorded as occurring at many places in the Russian 
Empire, “from the Lower Volga northward to the mouth of the Petschora.” Nordenskiold 
found it at Spitzbergen, and Lieut. Payer and Dr. Copeland, at Kuhn Island, off the east 
coast of Greenland. The exact age of the Awcella schists of Europe has been the subject of 
much discussion among geologists, and authorities are still at issue on this point. In the 
“Geology of Russia,” published in 1846, D'Orbigny places them in the Oxfordian division 
of the Jurassic. In the Moscow Journal for 1861, and in the second volume of the Lethea 
Rossica, which bears date 1867, Eichwald maintains that they are of Neocomian, and, there- 
fore, of Lower Cretaceous age. Trautschold, in the Journal of the German Geological 
Society (Berlin) for 1864 and 1866, claims that they are Jurassic, and about the age of the 
Kimmeridge clay, though, in a subsequent paper, contributed to the Moscow Journal of 
1875, he places them a little higher in the Jurassic system, in the Tithonic group of Oppel, 
and this latter opinion of Trautschold is endorsed by Rudolph Ludwig. 
Mr. Gabb has already shown that in California Aucellæ are among the most charac- 
teristic fossils of the Shasta Group, which is unquestionably Cretaceous, but it is now 
practicable to state more than this. The upper part of the Shasta group, which may pro- 
visionally be called the Queen Charlotte Island Group, is the equivalent of the Middle 
Cretaceous, and in this division, Awcellæ, though rare, are certainly present. The lower 
part of the Shasta Group corresponds to the upper part of the Lower Cretaceous, and it is 
in this division that Awcelle are so abundant. In America, as in Europe, the writer holds 
with Eichwald, that the presence of Aucellæ in abundance is a sure proof of the Neocomian 
age of the rocks in which they are found. Very few fossils have been found in the auri- 
ferous slates of California, and the few that have been found are both distorted and badly 
preserved. One of these, the Lima Erringtoni of Gabb, has been supposed by Prof. Meek to 
be probably identical with Aucella Mosquensis, and if this be the case, then these slates will 
probably prove to be of Neocomian, and not, as now generally supposed, of Jurassic age. 
ARCA, 
Two casts of a small Arca, which very much resemble the A. Carteroni of D’Orbigny 
in shape, one from the N. slope of Jackass Mountain, the other from the West bank of the 
Fraser, near the thirty-sixth mile-post on the wagon road to Yale. 
CUCULLAA. 
A small cast of a bivalve, also from Jackass Mountain, which appears to belong to this 
genus, but not in its most restricted sense. 
YOLDIA. 
À single valve from the Skagit River, but too imperfect and too badly preserved to be 
either identified or described. 
GRYPHGA, OR OsTR@A. 
Skagit River, one valve only. Possibly a variety of the Gryphea Nebrascensis of Meek. 
