[174] 310 
This fossil sipiarendly exists in gteat n numbers, as in the specimens ex- 
amined there were individuals in all stages of growth, though mostly 
broken or separated valves. The sam e species was collected byt the late 
Mr. Nicollet, near the Great Bend of the Missour 
Local ity, Sm moky Hill river, longitude 98°, laid 38°, i in yellowish and 
- gray limestone of the aS EP rmation 
25. Inocrramus 4, fig. 2. (D 
Inoceramus involutus, Sow n. Con de 
Descripti in Sarajelretita : ania: "flat, vith the margin deflected; 
marked by strong, regular concentric ridges, which become attenuated on 
either side, and are nearly obsolet bagel the beak; beak of one valve 
small, not elevated ; “hinge e li aapessalnge: 
3 The str strong concentric caves distinguish this fossil from any oter species. 
“The specimen —- is probably the flat valve, as a fragment of a large 
-andmuch more convex valve accompanies this one, from the same locality. 
The shell, ssieeseinidaly towards the margin, is very thick and fibrous. 
rthe eastern slope of the Rocky mountains, in longitude 
105°, tperette 3os 39°, i in light yellowish-gray limestone, probably of the creta- 
ceous formation. . 
a‘ 
0. 42 of collection. ) Compare 
© .. Norz.—The specimens figured on plate III, Nos. 1, 2, 4, 5, and 6, have 
appearance of fluviatile shells, and would have been so rega ed but 
the ovemampnce of fig. 3, which appears to be a Nucula, and: 
“known to me. ‘< not improbable, however, that this may prove a fresh-_ 
water hye 2 of vast interest, as it appears to be of great extent, : and oc- 
evation. The researches of Capt. Frémont, in his future 
doubtless set this question at rest, by a larger one 
of Fossils fi sag a same region. 
¥ 
