CONTRIBUTIONS TO PALEONTOLOGY. 49 



This shell has all the characters of the Genus Macrocheilus as occur- 

 ring in the Coal measures, and is the second well-marked species I have 

 observed in the Hamilton group. This species resembles the M. newberryi 

 of the Coal measures ; but the two last volutions are more ventricose, the 

 suture-line close, while the shell, of less length, has one more volution. 

 From the M. ventricosus it differs in the larger and less attenuated spire, 

 while the two last volutions are ventricose. 



Geological formation and locality. In the Goniatite limestone of the 

 Hamilton group at Manlius, N.Y. Collected by C. A. White. 



MACROCHEILUS HAMILTON^ (n.s.).tV. ^^ ^ • ^ iL. Zj-, 

 Shell very ventricose. Spire short, consisting of four or five volu- 

 tions, the last one extremely ventricose, making nearly two-thirds 

 the entire length of the shell. Aperture longitudinally oval, 

 obtuse below. Shell distinctly striated by fine lines of growth. 

 Suture-line deeply impressed. Length about one inch, with a dia- 

 meter of nearly three-fourths of an inch. 



This shell resembles in some measure the shorter and more ventricose 

 forms of the Coal measures, the spire resembling that of M. primi genius. 



Geological formation nad locality. In the coarse shales of the Hamilton 

 group at Hamilton, Madison county, N.Y. 



MACROCHEILUS (HOLOPEA) MACROSTOMUS (n.s.).^ / '^ 

 Shell short, subglobose. Volutions 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 the height of the 

 volution : greatest width of the shell equal to the height. Aper- 

 ture rounded, a little extended on the lower side. 

 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 striss some- 

 times crowded in fascicles. 



This species resembles in form some of the Platyostom^ ; but the 

 texture of the shell and surface-markings are not in accordance with the 

 well-marked species of that genus. In surface-characters and form of shell 

 it is similar to Holopea ; and having no positive knowledge of the aper- 

 ture and columella, it is impossible to decide that it may not belong to that 

 genus. 



Geological formation and locality. In calcareous beds of the Hamilton 

 group at Pratt's falls, Madison county, N.Y. 



1861.] 7 [Senate No. 116.] 



