178 Mr. Dillwyn on Fossil Shells. [March, 



shells may be observed which have hitherto escaped notice, and 

 if you should find them to be sufficiently interesting, or likely to 

 open a new door for inquiry, I beg that you will submit to the 

 Royal Society the following observations on the fossil remains of 

 the Molluscae. 



Pliny, in describing the shell fish which was supposed to 

 yield the Tyrian die, has observed, ' lingua purpurae longitudine 

 digitali, qua pascitur perforando reliqua conchylia ; ' and 

 Lamarck says, that all those molluscse whose shells have a notch 

 or canal at the base of their apertures, are furnished with similar 

 powers, by means of a retractile proboscis ; and in his arrange- 

 ment of invertebral animals they form a section of the Tracheli- 

 podes, with the name of ' Zoophages.' Whether all these 

 Trachelipodes are possessed of the same predaceous powers of 

 boring into hard substances, and whether 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 pur- 

 poses as the respiratory organs of a Gastrobranchus,* and may 

 serve at once to distinguish a carnivorous species. The follow- 

 ing fossil genera belong to this section of the Trachelipodes — 

 Conus, Oliva, Ancilla, Terebellum, Seraphs, Cypnea, Ovula, 

 Volvaria, Marginella, Voluta, Mitra, Terebra, Buccinum, Harpa, 

 Monocerus, Purpura, Cassis, Cassidaria, Strombus, Rostellaria, 

 Triton, Murex, Ranella, Pyrula, Fusus, Cancellaria, Potamides, 

 and Cerithium. 



In all the other genera of turbinated univalves, the lower mar- 

 gin of the aperture, instead of being either notched or chan- 

 nelled, is entire ; and Adanson, in his History of Senegal, so fin- 

 back as 1757, has shown that the Molluscee of these shells have 

 jaws which are formed for feeding on vegetable substances ; and 

 they have been proved, by subsequent observations, to be 

 entirely herbivorous, i. e. the marine genera feed on algae, and 

 the fresh water and land <;enera on the leaves of vegetables. 

 These together constitute the other section of the Trachelipo- 

 des, which Lamarck has called ' Phyti phages,' and it comprises 

 the following genera of fossils — Turritella, Turbo, Cirrus, Euom- 

 phalus, Trochus, Solarium, Delphinula, Scalaria, Natica, jVerita, 

 Ampullaria, Vivipara,+ Paludina, Melania, Planorbis, Cyclos- 

 toma, Auricula, Tornatella, Bulimus, Helicina, and Helix. 



Every turbinated univalve of the older beds from transition 

 lime to the lias, which I have been able to procure, or of which 

 I can find any record, belongs to these herbivorous genera, and 

 the family has been handed down through all the successive 



• 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 Vivipar* is 

 calculated to mislead, for none of the specie* are more than ovi- viviparous. 



