Foerste.] 
280 
[May 1, 
Orthoceras (eu-orthoceras?) hanoyerensis, sp. nov. 
(plate YI, FIG. 6.) 
The type specimen was found at Hanover, Indiana. It is 43 mm. 
long and contains in that length twenty-seven septa, the septa at the 
smaller end being 1.4 mm. distant from each other, those of the 
larger end, 2 mm. It has a diameter of 9 mm. at the smaller end, 
and 15.2 mm. at the larger extremity. A cast of the interior of the 
shell shows a faintly raised straight line along one side of the cast, 
scarcely .13 mm. wide ; on account of the curvature of the cham- 
bers of the shell along their lower edge this line is often not distinct 
except along the upper half of the cast of each chamber. The ex- 
terior of the shell is not well preserved. It certainly does not seem 
to have been strongly corrugated in any direction but appears to 
have been smooth, in the small portion preserved. More specimens 
are needed to decide this point. The septa are moderately concave, 
forming an arc of about 75°. The siphon is central and is com- 
posed of small oval-oblong annulations, placed between the septa. 
These annulations have a diameter of about 1.3 mm., near the mid- 
dle, decreasing in size as they approach the septa, through which 
they are connected by an aperture scarcely exceeding .75 mm. 
On the casts of the interior of the shell from a point 5 mm. on 
either side from the raised longitudinal line already described, the 
cast of each chamber is crossed by an oblique groove, which origi- 
nates at the lower side of the cast of the chamber and passes ob- 
liquely upward, reaching the upper side of the chamber after a 
distance of 10 mm. from the raised longitudinal line. It has been 
suggested that this groove corresponds to a similar groove on the 
surface of the shell, but no evidence for this statement is found in 
the specimen. The grooves just described are measured at a point 
where the shell is 40 mm. in circumference. Therefore the infer- 
ence is permissible that the structure just described is duplicated on 
the other side of the shell and that the groove after crossing the 
septal line continues for 5 mm. on either side until it reaches the 
upper septum of the chamber above. In that case it would be 
possible to conceive of this groove as continuous around the inner 
cast of the shell, beginning near a septum at the longitudinal raised 
line of the cast already referred to, and continuing to a point on 
the opposite side two septa above. A peculiar scalloped appear- 
ance on one side of the section of the shell is due to a concave 
