OF THE UPPER MISSOURI. 65 
genus Verebratula, as now restricted. It has a wide geographical range, and is almost everywhere the companion 
of Spirifer camerutus. Prof. Marcou figures it in his work on the Geology of North America, pl. 6, fig. 9, from a 
formation in the Rocky mountains, which he refers to the lower Carboniferous; but we have never seen it from 
any position below the Coal measures. 
Spirigera ? At Fort Riley, and above there, as well as in the same position on Cottonwood creek, we found, 
ranging from Division 18 up to 10 of the foregoing section, a Spirigera resembling S  subtilita, but much more 
gibbous in form; it also appears to have a much thicker shell. If distinct from S. subtilita this might be desig- 
nated by the specific name giblosa. 
LAMELLIBRANCHIATA. 
Monotis Hawni, Meck and Hayden. Trans. Albany Inst. vol. iv, March 2, 1858. Prof. Swallow thinks this 
species not distinct from M. speluncaria, Schlot. sp. Although, like that species, it is quite variable, and some of 
its varieties are very similar to it; after a careful comparison of a large number of individuals with Kine’s ficures 
and descriptions, we still regard it as distinct. We have never seen any of its various forms with the beak of the 
larger valve elevated so far above the hinge, as in figs. 5, 6, 7, and 8, pl. 13, of King’s work. Nor do any of our 
specimens possess the peculiar oblique posterior sulcus seen in the figures cited above. High country, south of 
Kansas falls; also above there, on Smoky Hill river and Cottonwood creek, in Division 10. 
Myalina (Mytilus) perattenuata, Meek and Hayden. Trans. Albany Inst. vol. iv, March 2d, 1858. Our 
description of this species was made out from one of the more slender varieties of this shell, sent to us from near 
Smoky Hill river by Mr. Hawn. We were probably wrong, however, in referring to it a specimen in our possession 
from a locality on the Missouri, opposite the northern boundary of Missouri; and we even suspect the rock from 
which this latter specimen was obtained may belong to an older epoch. 
The species above cited is, we think, identical with M. perm/anus of Swallow, Trans. Acad. Sci. St. Louis, vol. i, 
p- 187. And we also suspect the form he describes in the same paper as Mytilus (Myalina) concavus, is only a 
broader variety of the same; at any rate we have these two forms, and every intermediate gradation between them, 
from the same bed. Locality and position same as the preceding. 
Myalina squamosa. (Mytilus squamosa, J. de C. Sowerby. Morris’s Catalogue, p. 93. Myalina squamosa 
of some other authors.) 
Of the form, we refer with doubt to the above species; we have but one imperfect specimen. As far as the 
characters can be made out, it agrees with this species. We found it in Division No. 11, at Kansas falls, above 
Fort Riley. 
Myalina subquadrata, Shumard. Missouri Geol. Rept. 2d part, p. 207, pl. c, fiz. 17. Upper Coal measures, 
Leavenworth city, on the Kansas, at Lawrence and other localities in Kansas valley, below mouth of Big Blue river. 
Edmondia 2? Calhouni, Meek and Hayden. Trans. Albany Inst. vol. iv, March 2, 1858. We are still in doubt 
in regard to the generic relations of this species, having precured no better specimens than that first described by 
us. We suspect it may be a Cardinia. Near Smoky Hill river, in Division 10. 
Bakevellia parva, Meek and Hayden. Trans. Albany Inst. vol. iv, March 2, 1858. This is probably the same 
species referred by Prof. Swallow to Avicula antiqua, Munster,—Bakevellia antiqua of King, and others. In 
describing this species, we spoke of its very near relation to B. antigua, but.pointed out some characters in which 
it differs. At that time we had seen but a few imperfect specimens; since then, however, we have obtained many 
others, a careful examination of which causes us still to regard it as distinct from B. antigua. Of a large number 
of individuals, we have never seen any one-half the size of the smallest, nor one-eighth the size of the largest figures 
VOL. X11.—9 
