396 Mr. Dillwyn on fossil shells. 
S trombus Pes Pelecani; and it may be observed that this species, 
when fully grown, has not any open canal at its base ; and 
that in the figure which Muller has given of the animal 
there is no appearance, nor in Montagu’s description is any 
mention made, of that retractile proboscis or respiratory trunk, 
which are the distinguishing characters of a carnivorous Tra- 
chelipode. I therefore propose to remove these Rostellarias 
of the secondary strata, which are readily distinguished by 
the remarkable expansion of their outer lips, to form a se- 
parate genus with Petiver’s name of Aporrhais and the 
other fossil Rostellariae which have the recent Strombus fssus, 
for their type are only to be found in strata above the chalk. 
Small circular holes, which have been bored by the pre- 
daceous Trachelipodes, are frequently found in recent shells, 
and I have seen exactly similar holes in many fossils, but 
they have all been taken from the London clay or crag ; nor 
have I been able to find any such appearance in any fossil of 
the older formations. If this observation should be confirmed 
by a more extended examination of other cabinets, it will 
prove that neither the Aporrhaides, or any of those few un- 
doubtedly carnivorous species which have been found in the 
.secondary formations, were furnished with any such pre- 
daceous powers as Pliny has described, and that they belong 
to a subdivision of the Trachelipoda zoophaga, which feed 
only on dead animals. Without attempting to distinguish 
the more predaceous from these other genera, I shall how- 
ever at present content myself with proving, and for this I 
have adduced sufficient evidence, that the whole family of 
the carnivorous Trachelipodes are extremely rare in all those 
strata where the Ammonites and other Nautilidae abound. 
