TO GEOLOGY. 123 



The genus Solarium in England, where seven species 

 have been described, has been observed as low down in the 

 series as the Inferior Oolite. Mr Sowerby describes four 

 from the London Clay. M. Deshayes gives, in his Tables, 

 sixteen species from the Tertiary. Eight of these are from 

 the Eocene of the Paris basin, and six from the Pliocene of 

 the Subappennines. Mr Conrad has described a species 

 Jrom Claiborne, the elaboratum. 



GENUS ORBIS. (nobis.) 



Description. Shell orbicular, discoidal, umbilicate ; 

 mouth quadrangular ; umbilicus large, spiral ; all the 

 whorls on both sides visible ; columella none. 



I have in vain endeavoured to place the shell on which 

 I propose to found the above genus, in some one already 

 established. It appears to me to differ so essentially in 

 having quadrangular whorls, and of course having the 

 mouth of that form, that I could not with propriety place 

 it in the genus Solarium which it most resembles. It has 

 some resemblance to the genus J\faclurite (Lesueur), but 

 differs in the plane of the sides and the mouth. 



O. rotella. Plate 4. Fig. 112. 



Description. Shell flat above and below, bicarinate ; 

 apex rather impressed ; substance of the shell very thin ; 

 suture linear ; umbilicus wide, perspective, carinate on 



