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. 
The 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 mollusks as 
Euomphalus, to which genus the leading species, P. cristatvs , 
has been referred by Prof. Phillips. In the genus Ecculi- 
omphalus of Captain Portlock (Geol. Report on London- 
derry, p. 411) 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 am 
unwilling to believe it can include the fossils now under 
consideration. 
PHANEROTINUS cristatus. 
TAB. DCXX1V. — -Jig. 1 & 2. 
Spec. Char. Margin decorated with triangular 
foliaceous appendages. 
Syn. Euomphalus cristatus, Phillips, Geol. York. 
ii. t. IT/ 5. Morris , Cat. Brit. Foss. 144 & 1 5j. 
V olutions 4 or 5, the latter ones expanding rather more 
rapidly than those nearer the centre; one side more con- 
