102 The American Geologist. February, i897 
Large and normal looking specimens are rare at the base, hut common 
at the top of the Triplecia bed. Dwarfed ones are not known among 
those from the Leptaena bed (13). 
Compared to O. rogata, even the dwarfed ones of O. corpidenta are 
larger, the cardinal process is more perpendicular and longer; the mus- 
cle scars on the dorsal valve are more elongated, and the plication is 
coarser, i. e., a specimen of O. corpulenia has GO plications at least 
while an O. rogata of the same size would have 100 developed. 
The geologic relation of O. rogata and O. corpulenta would permit 
them to be considered as phylogenetically one species, but such a con- 
nection has not been traced. The change in the O. rogata from the 
Stictopora bed (no. i) to the Lingulelasma bed (8), and that in O. corpu- 
lenta from the Triplecia bed (10) to the Leptaena bed (13), is in each case 
less than the supposed change from the one to the other, the greatest 
change being necessarily, therefore, referred to the shortest interval. 
Among a few specimens seen of Orthis teatudinaria auct., from Trenton 
Falls, New York, one kind is, especially in coarseness of plication, more 
like Orthis corpulexta than like O. rogata, and the same is probably 
contemporaneous with the latter, and is the predecessor of the former. 
The two species vary in nearly like directions, but whether the greater 
tendency to develop dwarfish characters in the plication, as observed in 
the larger and later of the two, is inherited from dwarfed specimens of 
the earlier one, or are independently developed is not known. In the 
former case it could be that Orthis corpulenta Sardeson, had had the 
same ancestral origin as O. vmltisecta Meek, that in this the acquired 
dwarfish characters had developed farther, in the other less, and are 
seen to revert. Under the other theory, the two species are considered 
as contemporaneous, though closely related, as their surface ornamen- 
tation indicates. 
ORTHIS EIWACERATA Hall. 
PI. V, fig. 14 to 18, 28. 
Orthis emacerata Hall, (1860). Thirteenth Eep. N. York State Cabi- 
net Nat. Hist., p. 121; Fifteenth Rep., ibid, pi. 2, fig. 1, 2, 3. 
Orthis emacerata Meek, (1874). Paleontology of Ohio, vol. i, p. 109, 
pi. 8, fig. Id (not a, b, c, and 2). 
Ortiiis maerior Sardeson, (1892). Bull. Minnesota Acad. Nat. Sci. 
vol. Ill, p. 330, pi. 5, fig. 5, 6, 7. 
Orthis {Dalmanella) emacerata (1892). Paleontology of N. York, vol. 
viiT, pt. 1, pi. 5, C, fig, 1, 2. 
Orthis {Dalmanella) testudinaria var. emacerata. Winchell and Schu- 
chert, (1893). Final Rep. Geol. Nat. Hist. Sur. Minnesota, vol. iii, p. 445, 
pi. 33, fig. 23, 24. 
The types of the species are from near tlie middle of the Cincinnati 
shales (Hudson), at Cincinnati, Ohio, and specimens, together with 
O. midtisecta Meek, and O. meeki S. A. Miller, were collected there. 
Others, not different so far as seen, were found at the horizon of Trinu- 
cleus Goncentricus Eaton, in strata outcropping below high water mark 
of the Ohio river at Covington, Kentucky. In Minnesota the species is 
