394 
Mr. Dillwyn on fossil shells. 
ther some of them may not subsist chiefly on dead animals, 
my own observations have led me greatly to doubt ; but this 
notch or canal is made for the protrusion of a trunk, which 
is formed to answer the same purposes as the respiratory 
organs of a Gastrobranchus,* and may serve at once to dis- 
tinguish a carnivorous species. The following fossil genera 
belong to this section of the Trachelipodes — Conus, Oliva, 
Ancilla, Terebellum, Seraphs, Cyprasa, Ovula, Volvaria, Mar- 
ginella, Voluta, Mitra, Terebra, Buccinum, Harpa, Mono- 
cerus, Purpura, Cassis, Cassidaria, Strombus, Rostellaria, 
Triton, Murex, Ranella, Pyrula, Fusus, Cancellaria, Potamides, 
and Cerithium. 
In all the other genera of turbinated univalves, the lower 
margin of the aperture, instead of being either notched or 
channelled, is entire ; and Adanson, in his History of Senegal, 
so far back as 1757, has shown that the Molluscae of these 
shells have jaws which are formed for feeding on vegetable 
substances ; and they have been proved, by subsequent obser- 
vations, to be entirely herbivorous, i. e. the marine genera 
feed 011 algae, and the fresh water and land genera on the 
leaves of vegetables. These together constitute the other 
section of the Trachelipodes, which Lamarck has called 
* Phytiphages/ and it comprises the following genera of 
fossils — Turritella, Turbo, Cirrus, Euomphalus, Trochus, 
Solarium, Delphinula, Scalaria, Natica, Nerita, Ampullaria, 
■f-Vivipara, Paludina, Melania, Planorbis, Cyclostoma, Auricula, 
Tornatella, Bulimus, Helicina, and Helix. 
* See Sir E. Home’s observations on this animal under the name of Myxine, in 
the Philosophical Transactions for 1815, p. 261. 
f I am unable to distinguish this genus from Paludina ; and the name of Vivipara 
is calculated to mislead, for none of the species are more than ovi-viviparous. 
