TO GEOLOGY. 115 



the last described, differing, however, in being less elevated 

 and without striae. It has some resemblance to Jl. mela- 

 noides (Conrad), but has no striae. 



The genus Jlcteon has been observed in England, where 

 nine species have been described, as low as the Inferior 

 Oolite ; two are from the London Clay, and two from the 

 Crag. M. Deshayes s Tables give eleven from the Tertiary 

 period: being in all the three subdivided periods, Pliocene, 

 Miocene and Eocene. In the Tertiary of Maryland, at St 

 Mary s, Mr Conrad has observed two, ovoides and mela- 

 noides, described by him in vol. 6, Jour. Acad. Nat. Sci. 



FAMILY SCALARIANA. 



GENUS SCALARIA. Lamarck. 



S. planulata. Plate 4. Fig. 102. 



Description. Shell conical, closely ribbed, minutely and 

 transversely striate between the ribs ; substance of the shell 

 thick ; spire rather elevated ; ribs about twelve, rounded ; 



whorls , flattened, the last one only ribbed to the 



middle ; mouth round. 



Length .3, Breadth 3-20ths, of an inch. 



Observations. Having only a single specimen of this 

 species, and that mutilated, I am unable to give its charac- 



