79 
AMMONITES auritus. 
TAB. CXXXIV. 
Spec. Cuar. Compressed, with obscure radiating 
undulations tuberculated at their origin ; inner 
whorls exposed ; back deeply channelled, bor- 
dered by large alternating compressed tubercles. 
ee 
W nonrts four or five, the last nearly half the diameter, 
or twice the thickness of the shell long. 
Discovered in the micaceous sand when the Devizes 
Canal was digging, by Mrs. Gent, who favoured me 
with some other productions from thence some time 
since: the stratum to which they belong appears to 
require their aid to distinguish it. It is more or less 
micaceous, and in most instances there are only casts 
remaining of the forms that existed or were enveloped in 
it, and which have not yet been recognised in any other 
formation that I know of:* they are preserved in a pe- 
culiar way, being of so loose and crumbly a texture as 
scarcely to hold together, and a little change of wet and 
dry would soon fit them to be dispersed by the slightest 
wind ; but a certain depth has protected them in a place 
where they might have been preserved for ages more 
securely than in the most careful hands. 
* I have two or three species from Folkstone belonging to the same 
section as this, one of which I think is figured by Parkinson, Org. Rem. 
tab. 9, f. 8. 
