GASTEROPODA. 
33 
Macrocheilus Hamiltoni^e. 
PLATE XIX, PIGS. 8-14. 
Macrocheihts Hamiltoiiice, Hall. Descriptions of New Species of Fossils, etc., p. 21. 1861. 
“ “ “ Fifteenth Rep. N. Y. State Cab. Nat. Hist., p. 49, pi. 4, fig. 2. 1862. 
“ “ “ Illustrations of Devonian Fossils: Gasteropoda, pi. 12. 1876. 
Shell very ventricose. Spire short, consisting of four or five volutions, the 
last extremely ventricose, making nearly two-thirds the entire height of 
the shell. Aperture longitudinally oval, obtuse below. Shell distinctly 
striated by fine lines of growth; suture-line deeply impressed. Length 
about three-fourths of an inch, with a diameter nearly as great. 
This shell resembles, in some features, the shorter and more ventricose forms 
of this genus in the Coal measures, the spire* resembling that of M. primigenius. 
This species is almost equally rare with the preceding. 
Formation and locality. In the coarse shales of the Hamilton group at Ham¬ 
ilton, Madison county, N. Y. 
Macrocheilus (Holopea) macrostomus. 
PLATE XII, FIGS. 15-18. 
Macrocheilus ( Holopea) macrostomus, Hall. Descriptions of New Species of Fossils, etc., p. 21. 1861. 
“ “ “ “ Fifteenth Rep. N. Y. St. Cab. Nat. Hist., p. 49, pi. 4, fig. 3. 1862. 
“ “ “ “ Illustrations of Devonian Fossils: Gasteropoda, pi. 12. 1876. 
Shell short, subglobose. Yolutions, about four or five, all above the last two 
minute, the last one extremely ventricose, so that the width from the 
columella is about two-thirds its height; greatest width of the shell 
equal to the height. Aperture rounded, a little extended on the lower 
side ; umbilicus not closed. 
Surface marked by fine equal striae of growth, which are strongly directed 
backwards from the suture. Suture-line a little depressed below the plane 
of the convexity of the volution ; the striae sometimes crowded in fascicles. 
This species resembles in form some of the Platyostomae, hut the texture of 
the shell and surface markings are not in accordance with the well-marked 
species of that genus. Its surface characters and general form are similar to 
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