IN THE NORTHWEST. 599 
ranging between the Potsdam sandstone and the Niagara limestone; thirty-seven of which may be referred 
to species distributed through the Trenton limestone, Utica slate, and Hudson River group, as follows:— 
Cheetetes lycoperdon, Conularia Trentonense, Ambonychia undata, A. amygdalina, Nucula levata, Belle- 
rophon bilobatus, Pleurotomaria lenticularis, P. subconica, P. wmbilicata, Subulites elongata, Murchi- 
sonia subfusiformis, M. bellicincta, M. tricarinata, Cytoceras macrostomum, Orthoceras vertebrale, O. 
laqueatum, O. junceum, Lepteena planumbona, L. alternata, L. sericea, L. deltoidea, Atrypa hemi- 
plicata, A. modesta, A. capax, Spirifer biforatus, Orthis testudinaria, O. tricenaria, Lingula quadrata, 
Lchino-encrinites anatiformis, Heterocrinus heterodactylus, Calymene senaria, Isotelus gigas, Illenus 
crassicauda, Ceraurus pleurexanthemus, Phacops callicephalus, and Lichas Trentonensis. 
One species, Gonioceras anceps, is peculiar to the Black River limestone : one, the Orthoceras multica- 
meratum, to the Bird’s eye limestone; and one, Maclurea magna, to the Chazy limestone. 
Four appertain to the Clinton and Niagara groups :—Pentamerus oblongus, Atrypa reticularis, Leptena 
depressa, Catenipora escharoides. 
Among the species from the Devonian rocks on the Upper Mississippi, between Parkhurst and New 
Buffalo, and at the other localities in the Northwest, more than two-thirds are identical with species occur- 
ring in the shell and coralline beds of the Falls of the Ohio, in the vicinity of Louisville, and Charleston 
landing, Indiana. ; 
The Onondaga limestone and Hamilton group of New York are represented by the following species :— 
Leptena depressa, L. inequistriata, Atrypa reticularis, A. concentrica, A. aspera, Spirifer macro- 
notus (2), S. mucronatus (?), S. congesta, Pleurorhynchus trigonalis, Phacops crassimarginata, P. ma- 
crophthalma, and Favosites gothlandica. This list will doubtless be greatly extended, when the forth- 
coming volumes on the paleontology of the higher rocks of the New York system appear, as they will 
afford means of comparison between the fossils of the two districts, not now at our disposal. 
Thirteen species are identical with European forms, as follows :—Lucina proavia, Spirifer heteroclytus, 
Atrypa reticularis, A. aspera, A. concentrica, Orthis resupinata, O. umbraculum, Chonetes nana, 
Phacops macrophthalma, Astrea ananas, A. hexagonum, Stromatopora polymorpha, Favosites gothlan- 
dica, and Favosites polymorpha. Of these, several belong exclusively to the Devonian strata in that 
country, while some extend downwards into the Silurian, and some above into the Carboniferous beds. 
Of the one hundred and twenty Carboniferous species collected chiefly in the State of Iowa, twenty-four 
are European species; these are—Cheetetes capillaris, Lithostrotion floriforme, Conularia quadrisulcata, 
Chonetes variolata, Orthis umbraculum, O. Michelini, O. resupinata, Terebratula plano-sulcata, T. lamel- 
losa, T. Roissyii, T. sacculus, Productus punctatus, P. cora, P. Flemingii, P. costatus, P. semireticu- 
latus, P. carbonarius, Spirifer striatus, S. cuspidatus, S. lineatus, S. rotundatus, Fusulina cylindrica, 
Platycrinus granulatus, and Poteriocrinus plicatus. 
It is remarkable, that, while more than one-half of the Brachiopoda of this system can be referred to 
European species, only two out of the fifty-two Crinoids (described and undescribed), have been recog- 
nised as common to the two countries. ; 
From the foregoing, it appears, that the Brachiopoda of these western palozoic groups embrace the 
greatest variety of species: the Silurian period furnishing the greatest number of this order ; the Carboni- 
ferous next; while the Devonian rocks have as yet supplied the fewest. This is partly to be accounted 
for, however, from the limited area over which this latter group of rocks is accessible. The Crinoidea 
rank next to the Brachiopoda, in the abundance of species; about nine-tenths of these are from 
the Carboniferous age. 
Next to the Crinoidea, in numerical importance, come the Crustacea; this order being by far the most 
numerous in the Silurian period, which has furnished four-fifths of the whole number of species. The 
Cephalopoda and Gasteropoda are next most abundant; the latter system affording the greatest amount 
of species. : : 
The Polyparia, on the other hand, appear to be most abundant in the Devonian rocks; indeed, some 
of these beds, in Iowa, are made up almost entirely of corals. The Acephala appear to be most abundant 
in the Silurian and Carboniferous rocks. Only two or three species of Pteropoda have as yet been found, 
two of which appear in the Silurian rocks, and one in the carboniferous, which formations have afforded the 
only species of Foraminifera yet obtained. - 
If we may judge from the abundance of coralloid limestones in the Devonian’ period, and the purity of 
these calcareous beds, with little siliceous and argillaceous intercalations, we are perhaps justified in con- 
