29 

 PHANEROTINUS. 



Gen. Char. Shell a convoluted tube, discoid ; 

 whorls several, not touching each other, ar- 

 ranged nearly in a plane ; aperture roundish ; 

 substance thick, composed of several coats. 



Ihe shells of this genus are composed of a thick tube 

 which is wound about a transverse (in this case an imagi- 

 nary) axis, as it is in Ammonites : but the whorls expose 

 their whole surfaces. The general form is discoid; and 

 the two sides of the disc being nearly alike, although not 

 precisely so, I consider the tube as convoluted, and that it 

 may possibly not belong to the same order of moUusks as 

 Euomphahis^ to which genus tiie leading species, P. cristatus, 

 has been referred by Prof. Phillips. ]n the genus Ecciili- 

 omphahis of Captain Portlock (Geol. Report on London- 

 derry, p. ^ll) the shell is much less curved, and very thin; 

 its general aspect also is so different, that although it may 

 not be easy to frame a satisfactory generic character, I aui 

 unwilling to believe it can include the fossils now under 

 consideration. 



PHANEROTINUS cristatus. 



TAB. DCXXIN.— fig. 1&2. 



Spec. Char. Margin decorated with triangular 

 foliaceous appendages. 



Syn. Euomphalus cristatus, Phillips, Geol. Yoi'k. 

 ii. t. \3.f. 5. Morris, Cat. Brit. /^ss.I44& 155. 



V oLUTioNS 4 or 5, the latter ones expanding rather more 

 rapidly than those nearer the centre; one side more con- 



