10 GEOLOGICAL SURVEY OF THE TERRITORIES. 
form described by Mr. Meek, there are many also which are not so much 
elongated, but which are evidently of the same species. This remark 
applies not only to the young, which were proportionally short, as shown 
by the lines of growth upon the anterior portion of adult shells, but also 
to many that are massive and evidently of adult growth. SjAill, the spe- 
cies has always much more than the average proportionate length. The 
habit of this oyster, mentioned by Mr. Meek, of uniting its shells in 
groups of three, by their deeper valves, is not confined to this species 
alone. I have often observed it in the case of O. glabra M. & H. of the 
Laramie Group. I suppose it to have been a not uncommon habit with 
oysters that-lived on sandy bottoms, because, in all the cases I have ob- 
served, the specimens were collected from soft sandstone strata; and 
yet in all these cases the majority of their associates of the same species 
were free. It is a common habit with oysters to attach themselves to- 
gether, but why they should so often have been attached together in the 
manner described is not easy to understand. 
Considerable variation in form is very common in all species of Ostrea 
proper, and some very elongate examples of the living O. virginica are 
occasionally brought into the markets from various places along the At- 
lantic coast. This fact was illustrated by a large labeled series pre- 
pared at the Smithsonian Institution by Mr. W. H. Dall for the Centen- 
nial Exposition in 1876. In reply to some inquiries, Mr. Dall writes me: 
“In the ease of O. virginica there is no doubt that a position where it is 
subjected to currents, and especially if the water carries a little sediment, 
will induce a long, thin growth, with parallel sides; while still waters 
tend to produce a rounded form. The normal is between the two. But 
there are normally long species and normally round, besides twig-climb- 
ing species, all of which, in a state of nature, may be differently affected 
from thinned and planted oysters.” 
There is no room for doubt that Ostrea soleniscus is a normally long 
and slender species. That its elongate form is not due to the same cause 
which elongates the specimens of O. virginica before referred to is Shown 
by the fact that so many of the longest of them are found in a vertical 
position, evidently their natural one, in relation to the plane of the strata 
containing them, as mentioned by Mr. Meek, and also observed by my- 
self. It is also contra-indicated by the fact that so many of them grew 
in clusters of three, attached together by their larger valves, and by the 
absence of any evidence in the character of the strata that they were de- 
posited in water having a current of sufficient strength to produce such 
a result. 
I know of no other American oyster, either fossil or recent, that need 
be confounded with this species The anterior portions of many of the 
specimens, as they are often found broken off, resemble corresponding 
portions of O. longirostris Lamarck, as figured by Goldfuss; but although 
that species is an elongate one, O. soleniscus is constantly a much more 
slender species. 
OSTREA ANOMIOIDES Meek. 
Plate 11, figs. 4a and 0. 
Ostrea anomioides Meck, 1873, An. Rep. U. S. Geol. Sur. Terr. for 1872, p. 488. 
No other examples of this species besides those of the original collec- 
tion have ever been obtained. The figures on plate 11 are drawn from 
Mr. Meek’s types, and the following is his description of the species, 
together with his remarks upon it: 
‘Shell rather small, very thin, depressed-plano-convex, and without 
