NATURAL SCIENCES OF PHILADELPHIA. 131 



Bellerophon nautiloides, Win., (Proc. Acad. 'Nat. Sci. Phil. Sept. 1862, p. 

 427.) Collected by A. W., at Alan's quarry, Hillsdale, Michigan. 



Conrad has described B. stamineus, from Moscow, Hillsdale county, Michi- 

 gan, at which place I have observed both B. nautiloides and B. galericulatus, 

 Win., and it is probable that he had one of these species in view in his de- 

 scription. The ten words employed in the description, however, will apply 

 equally well to half a dozen species of Bellerophon ; and it is hence utterly im- 

 possible to avail myself of the results of his studies.* 



Bellerophon cyrtolites, Hall. This widely distributed species has been 

 found at Alan's quarry, Hillsdale, Michigan. I 



Pugiuncuxps ? AC0LEATUS, Ha"ll. This Rockford species has been collected 

 by A. W., at Alan's and Germain's quarries, Hillsdale, Michigan. 



Dentalium ? Barquense, Win., (Proc. Acad. Nat Sci. Phil., Sept. 1862, p. 

 425.) Additional specimens from the same locality, show that the short tubes 

 supposed to belong to the shell structure, are not always normal to the sur- 

 face ; and that when the internal cylinder is removed, so as to afford a view 

 of the inner surface of the prismatic coating, the oblong sections of the prisms 

 as they were applied to the cylinder, look somewhat like the polyp cells 

 shown in longitudinal sections of some branching corals ; and there is seen 

 also something like the same divergent disposition of the tubes. Moreover, 

 the structure is extremely like that referred to in the last paragraph of my 

 paper in the Proceedings for Sept. 1862, p. 430. This latter structure U folia- 

 ceous, but occurs at the same locality. Can these rigid stems, then, be corals 

 with very large hollow axes ? 



METOPTOMA, Phillips. 



Metoptoma undata, n. sp. Shell of medium size, nearly erect, apex nearly 

 central, aperture transversely slightly elliptic; body of shell most inflated in 

 the middle, somewhat acuminate toward the apex, and contracted at the 

 aperture. Cast nearly smooth over the body of the shell, longitudinally un- 

 dulate near and at the aperture, with a few wavy concentric lines of incre- 

 ment. 



Height of shell, 1*15 (100) ; longest diameter of aperture, T06 (92). 



From Bed "No. 5," Burlington, Iowa. " White Collection" of the Uni- 

 versity of Michigan. 



The inferior side of the only specimen seen is defective ; yet there are in- 

 dications that it was flattened, as in the typical species of Prof. Phillips. 



Platyceras paralkjm, White and Whitfield. Identified in the Lithographic- 

 limestone of Clarksville, Missouri. " White Collection." 



A variety more robust than the typical form, and wanting in the longitudi- 

 nal folds which characterize the latter, occurs in the base of the Burlington 

 limestone at Burlington. 



Platyceras vomerium, Winchell. From Sheldon's saw-mill, Big Brook, 

 Orange, Cuyahoga county, Ohio, below grindstone grit. Whittlesey's collec- 

 tion. 



The Ohio specimens have a dorsum not quite so acute as the Iowa types, 

 and an aperture a little less expanded. 



PLEUROTOMARIA, Defrance. 



Pleurotomaria quinquesulcata, n. sp. Shell of medium size depressed 

 conical, consisting of three or four rapidly enlarging whorls. Outer whorl 



* In the 4th line of my description of B. galericulatus, (!oc. cit. p, 426,) fur " ventrally," read 

 " retrally." 



1865.] 



