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PROCEEDINGS OF THE ACADEMY OF 
resembles C. setigera , Hall, and C. nana, but differs from the former in 
having oblique instead of erect spines, and from the latter in the smaller area 
of the ventral valve. C. setigera occurs in the Hamilton and Chemung of 
New York, and I have identified it in the blue argillaceous shales of the Huron 
group of Michigan. C. nana is found in the corniferous limestone ; and Euro¬ 
pean geologists regard it as a Devonian species. 
Chonetes Illinoisensis, Worthen, (Trans. St. Louis Acad. Nat. Sci. i. 571) ; 
C. Logani, Hall, (Iowa Rep. p. 598, pi. xii. fig. la—e and 2) ; not C. Logani, 
Norwood and Pratten, (Jour. Acad. Nat. Sci. Phil. [2] iii. 30, pi. ii. fig 12, 
a, b, c] ; C. Illinoisensis , Winchell, (Proc. Acad. Nat. Sci. Phil., Jan., 1863, 
p. 5). This wide spread species occurs at the Grindstone quarries at Pt. aux 
Barques, Mich. The specimens are smaller than the typical ones from Bur¬ 
lington, Iowa, and perhaps for this reason do not number as many striae 
around the margin ; but specimens from Burlington of the same age cannot 
be distinguished. 
Collected also by A. Winchell at Rockford, Indiana. It also occurs in the 
base of the Burlington limestone at Burlington, Iowa, (“ White Collection”) 
and in the fine grained sandstones of Licking County, Ohio. 
This species may be confounded with C. Shumardiana , De Koninck ; but 
the latter has 270 to 280 or more radiating striae, which are less distinctly 
isolated from each other. The former has from 100 to 125 striae. 
Chonetes geniculata, White, (Proc. Bos. Soc. Nat. Hist. ix. 29). A single 
ventral valve, collected by A. Winchell at Rockford, Indiana, cannot be dis¬ 
tinguished from this species. 
Chonetes Logani, Norwood and Pratten. In a former paper I pointed out 
the error of Hall’s identification of C. Logani , N. & P., though this species 
had not at that time fallen under my observation, and, I believe, has been 
seldom seen since first described. I have now, however, in some later addi¬ 
tions to the “ White Collection ” of the University, a number of examples of 
C. Logani , N. & P., fully answering to the original description and figure. 
These specimens are from the base of the Burlington limestone, and the ma¬ 
trix holds C. Illinoisensis in the same association, as previously believed. 
C. Logani , N. & P., as far as I have observed, is restricted to the horizon 
of the Marshall or Burlington sandstone—including the base of th‘e Burlington 
limestone, which belongs evidently to the same epoch. Prof. Hall, however, 
has a small Chonetes from the Tully limestone, which, he informs me, he has 
decided to refer to C. Logani , (see 11th volume Palaeontology of N. Y.), a 
reference to which, with full acknowledgement of his superior authority, I 
cannot, at present, give my assent. The Tully limestone species presents a 
series of concentric rugosities or wrinkles, which extend both across the ribs 
and the intervals between the ribs ; while in C. Loggni the rugosities are 
feebler, and are confined to the crests of the ribs. 
C. Logani is also recognized in Ohio, with about 40 to 50 ribs. It hence 
appears that the species, like C. Illinoisensis , Worthen, and C. multicosta , 
Winchell, ranges from the Burlington limestone into the sandstone below. 
I may perhaps be permitted to add that some typical specimens of C. Logani 
in Prof. Hall’s cabinet, sent to him by Dr. Norwood, are imbedded in a matrix 
of oolitic limestone, such as occurs at the base of the Burlington limestone. 
Orthis Michelint, L’Eveille, occurs in Whittlesey’s collection from “Wa- 
verly sandstone, near Newark, Licking County, Ohio.’.’ Another Orthis from 
Akron, Ohio, resembles the Burlington species commonly referred to O. Va- 
nuxemi (?), but differs in the parallel direction of the dental lamellae, and in 
the very indistinct character of the radial striation. 
Still another Orthis , received from Dr. Shumard and collected at Sulphur 
Springs, St. Louis County, Missouri, is perhaps the species referred by the 
[July, 
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