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North American Species of Zonites, etc. 359 
Z. lasmodon, it has fully 8 whorls, is 64 mill. in diameter, the 
umbilicus 1 mill. wide, whilst /asmodon with 7 whorls is 7 mill. 
in diameter, with an umbilicus 2 mill wide: the Roan Mountain 
shell has also five parallel lamellee, while /asmodon has only two, 
or at most three, and does not show the successive rows of lamel- 
le which are characteristic of Andrewsi, radiating from the 
centre. 
From Z. significans it differs in its larger size, greater number 
of whorls, much wider umbilicus, and in the character of its 
internal denticles, which are long and winding on the wall of the 
whorl; while in stgnificans the denticles are simply erect and 
conical, with broad base. ‘The same differences distinguish it 
from multidentatus, which is still smaller than s¢gnificans, and 
has a much narrower umbilicus. 
Zonites macilentus, Shuttl. 
On pl. XV, fig. B, I give an illustration of what appears to 
be the true macilentus (see ‘Terr. Moll., II, p. 20), which seems 
to be distinct from /asmodon, judging by specimens lately re- 
ceived. 
Zonites multidentatus, Binn. 
For the sake of comparison with Z. ségnificans and allied 
species, | give on pl. XV, fig. F, an enlarged view of this 
species, more satisfactory than that given in Terr. Moll. U.S, 
Iif. 
Zonites significans, Bl. 
By an unfortunate oversight, another shell was used to illus- 
trate this species in Terr. Moll., V, p. 132. I here figure (pl: 
XV, fig. G) an authentic specimen. 
On pl. XIV, fig. F, I have given, for the sake of comparison, 
an illustration of Z. meltidentatus, the nearly allied species. 
Zonites cuspidatus, Lewis. 
In the Proceedings of the Academy of Natural Sciences of 
Philadelphia, 1875, p. 334, this is mentioned as probably a var. 
of Z. cerinoideus. 1 have received authentic specimens from 
