52 
PALAEONTOLOGY OF NEW YORK. 
below the suture, and moderately rounded below, leaving a distinct angle, over 
which the stride pass without deflection. On the last volution towards the 
aperture this angularity of the upper side becomes gradually obsolete, while 
the base of the volution is marked by a distinct carina in continuation of the 
suture-line. 
In figures 11 and 12 the penultimate volution, as represented, is not quite 
sufficiently convex, while the angularity at the base of the last volution is con¬ 
spicuous. In the specimen, fig. 13, there is no perceptible angularity of the last 
volution; while in the specimen represented in figure 14 there is an obtuse 
angularity, which appears more as if due to accidental pressure from above, 
flattening the base of the last volution. In the same specimen, however, there 
is a distinct angularity and flattened space on the summit of the next two 
» 
volutions above. In the specimen, fig. 15, the upper volutions are moderately 
rotund, and the last one rounded and ventricose. 
From this form to those figured on plate 12, as Callonemci Lichas, there seems 
to me an easy passage. However, I have, for the present, preserved the latter 
name and references, which, if the species prove identical, will supersede the 
name of bellatula. 
Formation and localities. In limestone of the age of the Upper Helderberg, 
near Columbus, Ohio, and at the Falls of the Ohio river. 
Callonema Lichas. 
PLATE XII, FIGS. 19-22. 
Platyustoma Lichas, Hall. Fourteenth Rep. N. Y. State Cab. Nat. Hist., p. 106. 1861. 
Isonema “ “ Illustrations of Devonian Fossils: Gasteropoda, pi. 12. 1876. 
Shell obliquely subconical ovate; spire elevated. Volutions about four or 
more, rounded upon the exterior, the earlier ones moderately expanding, 
and the last one becoming very ventricose. Aperture subovate, extended 
below. 
Surface marked by fine even strise of growth, which, on the last volution, 
continue over the periphery and disappear in the umbilicus. 
