Notes on a Collection of Fossils. 191 



Cephalopoda. Indeed all the species belong to one or the 

 other of the above groups except some amorphous, laminated, 

 porous structures that recall certain forms of the Stromato- 

 ^oroidca. 



The following species, all apparently confined to cherty 

 layers of the formation, may be noted: 



Metoptoma alta Whitfield. The collection contains speci- 

 mens apparently identical with the species described and fig- 

 ured by Mr. R. P. Whitfield under the above name in his 

 paper on Fossils from the Calciferous Sand-rock of Lake Chain- 

 plain, Bulletin of Am. Museum of Natural Histor}', Vol. II, 

 No. 2. The Iowa specimens referred to this species are 

 larger than those from Lake Champlain. With the above 

 occur two or three other species of Jlctoptoma. 



Triblidium, sp. There are a few forms presenting the 

 appearance of Cafiihts or Platyccras that probably belong to 

 this genus. 



Straparollus claytonensis n. sp. This is by far the 

 most common species in the collection. It resembles Euom- 

 ■phalus calciferus, Whitfield, Lake Champlain Fossils, p. 47, 

 Plate VIII, Figs. 12 and 13. The volutions are four or more 

 in number, circular in transverse section; umbihcus wide and 

 deep; spire sometimes almost flat, usually sHghtly elevated. 

 From E. calciferous W., this species will be distinguished by 

 the fact that the volutions, in the cast, are not embracing, 

 scarcely touching each other, and the volutions are not coiled 

 in the same plane. The tvvo forms are about equally robust 

 and the whorls expand at about the same rate. Straparollus 

 claytonensis differs from^ Euomphalus strong i Whitfield, in 

 the greater number of less rapidly expanding volutions, the 

 absence of carinEe or angles on the whorls and the pro- 

 nounced difference between the umbilical and opposite sides. 



Straparollus pristiniformis, n. sp. This is a smaller 

 form than the preceding; volutions less robust, not embracing 



