30 Dr Boue's Observations on the 



all the series of fossils, we would see a great many species from 

 one locality, identify themselves with those of others, because 

 the connecting links would be present. In short, conchologists 

 do not possess the means of fixing the specific characters, and 

 sometimes not even those of the genera ; this can only be done 

 by the study of the animals, without which no one can trace a 

 strict line of separation between the accidental and specific cha- 

 racters of the species of fossils or of shells.''* 



But we must now return to xhe petrifactions or Jbssils of Gos- 

 san, The state of preservation of the fossils, as Brongniart well 

 observes, is a character of no importance ; for, according to this 

 character, we could classify, in the tertiary class, certain fossils 

 from the Lavatsch Alpine Valley in the Tyrol, from Raibel in 

 Carinthia and even sometimes transition shells, or place in secon- 

 dary formations some tertiary shells. The learned gentlemen ad- 

 mit that " out of more than 100 .different species^ there are from 

 30 to 40 bivalves, and of those capable of being identified, near- 

 ly equal numbers are referable to the youngest secondary^ and 

 the oldest tertiary, formations. The univalves are much more 

 numerous, especially in the quantity of each species, a fact sel- 

 dom remarked in secondary deposites. Among upwards of 50 

 species, 3 only are found in the chalk or greensand, whilst 

 7 species are identified with known tertiary fossils ; and several 

 of the genera, such as Volvaria, Pleurotoma, and Voluta, are 

 seldom, if ever, found in any deposite below the surface of the 

 chalk.''^ They admit, in this way, at Gossau, more than 50 new 

 fossils, which geognostical classification they do not give us ; be- 

 sides, in their conclusions, they do not exclude any of the fossils 

 from the recent secondary formations ; but remain satisfied that, 

 heretofore, certain fossils had not been found, or were very scarce, 

 in those secondary formations, which have been well studied only 

 in England, and in a few places in France. The greensand fossils 

 have much greater affinity with tertiary fossils, than with those of 

 older secondary rocks. They admit hippurites in the Gossau 

 rocks, but we suspect that this fossil is only accidental, and is a 

 rolled mass of hippurite limestone taken up and enclosed in the 

 rock, forming the base of the deposite. On the other hand, they 

 are not willing to believe that the Gryphcea columba may be 

 found at Gossau, at least they do not speak of the fact adduced 



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