254 
AUG. F. FOERSTE 
them.” Further study of typical specimens is necessary to de- 
termine the exact structure of the siphuncle. 
44. POTERIOCERAS McGOY 
Genotype: Orthoceras fusiforme Sowerby. See Foord, Garb. Foss, 
Ireland, pi. 15 
The name Poterioceras was proposed by McCoy for certain 
Carboniferous species, the generic description being : '‘Shell fusi- 
form. Mouth contracted. Siphuncle dilated between the 
chambers, excentric.” Blake states that the diagram accompany- 
ing this description is not justified by any known species, and 
represents the aperture as very small but simple. 
The species mentioned first in the body of the text is Poterio- 
ceras fusiform (Sowerby) from Boland, Kildare. This was 
founded on a specimen 6 inches long, 6 lines wide at the small 
end, one inch and 7 lines wide at its largest diameter, and 9 lines 
wide at the aperture. 
A study of a specimen from Kildare, Ireland, numbered 2177 
in the Museum of Comparative Zoology at Harvard University, 
(Plate XLI, Figs. lA, B) indicates the following characteristics: 
Conch fusiform, curved lengthwise, with the ventral side con- 
vex, and the dorsal side concave, except along the upper part of 
the phragmacone and the lower part of the living chamber 
along the dorsal side, where the outline is distinctly convex or 
gibbous. Toward the base of the living chamber the sutures rise 
from the ventral toward the dorsal side of the conch. The 
siphuncle is located a short distance ventrad from the center of 
the conch. The septal necks are short and curve distinctly down- 
ward and outward. The connecting rings are elongate elliptical 
in outline. The aperture appears to have been circular in out- 
line and its margin directly transverse. There may have been a 
shallow hyponomic sinus, but this is not indicated by the speci- 
men at hand. Conchs of this jtype do not occur in Silurian or 
Ordovician strata, 
Poterioceras fusiform (Sowerby) was figured by Foord^^ and 
one of his illustrations is reproduced herewith (Plate XL, fig. 2). 
Poterioceras latiseptum Foord^^ likewise shows the rise of the 
sutures of the septa from the ventral toward the dorsal side of 
Sowerby, Mineral Gonchology, pi. 588, figs. 1, 2. 
Foord, Garb. Geph. Ireland, 1897, pi. 15. 
^ Idem, pi. 16. 
