OHIO STATE ACADEMY OF SCIENCE. oY: 
Arcuaceras Ohioense, gen. nov. 
(Plate IX iMies22, “Slichtly reduced.) 
Shell large, abraded on both sides, very flat, only 11 
chambers left, making a length of 33 inches. Habitation 
chamber wanting, volutions about three, increasing moder- 
ately in size, sharply edged, septa deeply concave, arching 
rapidly forward in sharp sinuses over the dorsum; trans- 
verse diameter must have been from 5 to 6 inches. A faint 
trace indicates the siphuncle running just under the sin- 
uosity of the septa. 
This sinuosity of chambers near the dorsum consti- 
tutes this fossil a new genus among cephalopoda. 
Corniferous limestone, Columbus, Ohio. 
Arcuaceras termicameratum, sp. nov. 
(Plate X. Fig. 23. Reduced.) 
Shell below medium size, discoidal, rounded over the 
dorsum apparently (although badly fractured); sides 
abraded; chambers very shallow and only nine preserved, 
which being very thin about the umbilicus, widen toward 
the sinuosity of the dorsum where the arch of chambers is. 
high but gentle. The inner parts of chambers thin them- 
selves together to a space of 3-8 inch, while the dorsum of 
the same number measures 14 inches. Umbilicus must have 
been thin; siphuncle not known; its diameter likely 23: 
inches. 
Corniferous limestone, Columbus, O. 
