8 [857] A. Wincliell on supposed New Cephalopods. 
in length, partly septate. It is a fragment of a shell about 33 
inches long, having a major apical angle of 11°. The section is 
elliptical, with the minor axis to the major as *24: *45=1'88. 
The first two septa are ’08 apart, and the ratio of this interval 
to the larger diameter at the same point is 6 25. The septa are 
deeply concave, oblique, and slightly sinuous, having one side 
T2 in advance of the other. The greater diameter of the speci¬ 
men is *7 at one end and *45 at the other. 
Locality. In the Marshall sandstone at Hard Wood Pt. one 
mile S.W. of Pt. au Pain Sucre (called also Flat Rock Pt.) on 
the shore of Saginaw Bay. 
Ortiioceras reticulatum. ? 
Phillips (Geology of Yorkshire, vol. ii, p. 238; pi. xxi, fig. 11). 
The brief description given of this Carboniferous species does 
not disagree with the Michigan specimen in my possession. The 
figure agrees equally well. The fragment in question is 1J 
inches long, and shows only the exterior markings. Judging 
from the curvature of the specimen, it had a diameter of *89 in 
the constriction between two rings, which are ‘32 apart. The 
surface is marked by longitudinal and transverse stride; the 
former are fine, raised, equidistant, 13 or 14 being embraced in 
the space of one-tenth of an inch; the latter consist of two sets 
•—first, a set of irregular inequidistant, impressed striae of which 
3—6 occur in the space of one-tenth of an inch; secondly, a set 
of fine, regular, equidistant, filiform striae, of which about 32 
occur in the space of one-tenth of an inch. The latter give a 
finely moniliform appearance to the longitudinal striae, but they 
are most distinctly seen after the exterior of the shell has been 
removed. Characters of the siphon and septa unknown. 
Locality. In the Marshall sandstone at Marshall. 
Orthoceras sp. ? 
The only specimen seen of this species is a mere impression 
of the exterior, about an inch in length. It is made by a shell, 
apparently, with a circular section, and ornamented by a series 
of rounded rings, separated from each other b}^ a concave de¬ 
pression about twice the width of the ring. The whole surface 
is further marked by distinct longitudinal stride, about one one- 
hundredth of an inch wide. These' seem to increase by inter¬ 
polation of other striae, which begin to make their appearance 
when the first ones are one and one-fourth hundredths of an inch 
wide, and look like a finer set of striae alternating with the 
coarser. The diameter of the specimen, supposing the section 
circular, was about *84 in the grooves between the rings, and 
the elevation of the rings is ’03. The distances of four succes¬ 
sive rings, from center to center, are T5, T8, *21 and *21. 
Locality. Marshall. 
