Mineralogy and Geology. 277 
from the Corniferous limestone ; Hamiltonia, from the Hamilton group ; 
and a variety of the latter from the Chemung group. species from 
genus Trematospira, proposed in vol. ili, and published in the 
Tenth Report on the State Cabinet, is represented in the Hamilton group 
by two species: 7’. gibbosa, hirsuta. 
The genus Rhynchospira is represented only by a single species, the 
lida. The R. nobilis from the Hamilton group, formerly referred 
to this genus, presents some points which render its generic relations 
more nearly with Trematospira. ; 
The genus Nucleospira is represented by a single species, the WV. con- 
cnna, 
* 
the Hamilton group of Towa. A second species in the Hamilton group 
e genus Meristella, separated from Athyris on account of its different 
external characters and muscular impressions, is represented by M. na- 
sula, scitula, Doris, Barrisi, Haskinsi, rostrata, Meta (n.s.). In the 
emung group, there are a few casts of an undetermined species. The 
Meristelia unisulcata of the Corniferous limestone is referred to the sub- 
genus? Pentagonia of Cozzens, and its varieties of form illustrated. The 
Species is of rare occurrence in the Hamilton group. #%: 
The genus Atrypa, as applied to forms strictly congenerie —— 
sa (Hall), or Atrypa aspera 
gnized as t and well-marked species, 
S¢curring in the Corniferous limestone, Hamilton and Chemung groups. 
Saseenes it i a te | than 
'S of rare occurence in the rocks of New York. 
