weno 
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or Oe ae 
A. Winchell on supposed New Cephalopods. 355 
ant ORTHOCERAS ROBUSTUM, N. sp. 
A septate fragment of this species has such a curvature that 
the individual must have been 3:4 in diameter. Amongst other 
fragments of the last chamber of the shell, one is so large as to 
imply a diameter of 4:6. The septa appear to be transverse, 
separated from each other ‘31, where the diameter is 3°4, giving 
aratio of 11. In another specimen this ratio is "15: 98=6°54. 
No surface markings are indicated upon the casts. Siphon not 
Localities. Marshall, Moscow and Hanover in Jackson county. 
This species has the size and general appearance of 0. gigan- 
tum Sow. (de Kon., op. cit., 510, pl. xliv, 2; xlv, 3; xlvi, a, 4; 
uvii, 1), but differs, as far as observed, in having the septa sep- 
by one-sixth to one-eleventh of their diameter, instead of 
one-third. It differs from 0. crassum F. Rim. (Sandberger, 
Versteinerungen,” p. 164, Taf. xix, fig. 1) by a much greater 
‘pproximation of septa; and this reason, as well as its very 
great size, has induced me to separate it from O. Indianense. 
256; ratio of concavity of septa to their diameter “07 : °22=3'14. 
phon apparently slightly excentric. Surface (of cast) marked 
by delicate encircling bands, separated by rather sharp, fine 
Thon’ four of these bands correspond to each chamber. 
The single specimen in my possession differs from Sandberger’s 
description only in the words “taeniis transversalibus paullo ob- 
Mus. It differs from O. bicingulatwm Sandberger (Verstein., 
8, Taf. xvii, 3) in the transverse direction of the rings, and 
the perfectly circular section. 
ORTHOCERAS ARCUATELLUM. ? 
Sandb. (Verstein, 166 ; Taf. xix, 2). 
Shell tapering to an angle of 12°; nearly smooth externally, 
with faint, encircling, unequal, irregularly sinuous stris ; section 
“reular; septa transverse, with a convexity " to one-sixth 
: ! $ 
Locality. In the Marshall sandstone at Marshall. 
The general characters of this shell vane a good agreement 
with the species to which I have dou tfully referred it; but it 
iS €asy to point out differences, Our shell has a much less rapid 
taper, and the encircling striz are much finer, more unequal, 
and not regularly reflexed on the anterior and posterior sides ; 
Moreover, no observations have yet been made on the depth of 
