Antediluvian Zoology a?id Botany, 



28 1' 



Illustrative Group 



Univalves. 

 a, Limnea, I. Wight, Fresh-water. 

 by Planorbis, Isle of Wight, Fresh- 

 water. 



c, Murex, or rather Fusus, contra- 



rius; SuiFolk, Crag. 



d, Rostellaria macroptera,, Barton, 



London cjay. 



Bivalves. 



<?, U^nio, Hordwell Cliff, Fresh- 

 water (lower). 



/, Cjclas, Woolwich, Freshwater 

 (lower), or Plastic clay. 



of Shells: — 



g, Pholadomya (Cardita), Glouces- 

 tershire, Lias. 

 h, Terebratula, Suffolk, Crag. 



Complicated Bivalves. 



f, Spirifer, Derbyshire, Mountain 



limestone. 

 ky Pentamerus, Ludlow, Transition 



limestone. 



Chambered or Mtdtilociilar Univalves. 



/, AmmomteSy Folkstone, Gault. 

 m, Baculites, Chalk and Chalk 

 marl. 



v 



When the shellfish that inhabit our ocean are compared 

 with the fossil tribes, essential specific differences are per- 

 ceived ; and these differences become more striking as we 

 recede from the latest formations. In our crag and fresh- 

 water beds some species may be discovered which possess a 

 strong similarity, if not absolute identity, with those living in 

 our lakes and seas. Even here, the identity is maintained but 

 by a limited number, which are intermixed with numerous 

 others that have no recent analogues. Investigations in fossil 

 conchology lead, therefore, to one result ; that, with the incon- 

 siderable exceptions that have been stated, the species have 

 not been perpetuated to our times. 



We have seen that fossil remains of peculiar character oc- 

 cupy certain parts of the grand series of conchiferous deposits ; 

 but this transition is seldom abrupt. The same organic remains 



Vol. III. — No. 13. u 



