1867.] ( 409 ) 



8. GEOLOGY AND PALAEONTOLOGY, 



. {Including the Proceedings of the Geological Society.) 



An account of a most important work, entitled c Thesaurus Siluricus,' 

 was read by its author, Dr. Bigsby, before the Koyal Society, on 

 February 21st, and has since been published in the Society's 

 * Pioceedings.'* This ' Thesaurus' is a catalogue of all the fossils 

 which have been described from Silurian deposits in all parts of the 

 world, and gives the range of each species in space and time. In 

 the summary of results now made public are many facts and con- 

 clusions which are important, and some which are curious ; but all 

 are interesting. We thus find that there are 3,145 known American 

 Silurian species and 4,325 European ; but only 179 are common to 

 the two regions. The Primordial Zone is the first formation in 

 which anything like a fauna has been discovered, and in this 

 deposit we suddenly become conscious of the creation of more 

 than 900 species, belonging to a majority of the classes of the 

 Invertebrata. Species are treated of by the author under two 

 aspects, namely, (1) as being typical of one horizon ; and (2) as 

 " recurrent," or occurring in more than one. He finds that 12 per 

 cent, of the whole number of species occur in more than one horizon, 

 and that " the same species may be typical of one horizon in one 

 country and recurrent in another." All these recurrents are, of 

 course, within the limits of the Silurian epoch, and Dr. Bigsby 

 treats of them as intra-epochal. Those species which pass into the 

 Devonian period are termed extra-epochal, and he has been able to 

 identify 42 which come under this head ; and only one of these 

 (Chonetes sarcinulata) is known to have survived in Carboniferous 

 times. It is worth notice, also, that these extra-epochal recurrent 

 species were of migratory habits, — " few being found in two epochs 

 in the same country, but in different countries." 



We are glad to learn that the Eoyal Society has granted 100Z. 

 towards defraying the cost of publishing this work, and we look 

 forward to its appearance with some impatience. It is only by such 

 laborious endeavours as this that we can hope to discover the laws 

 which have regulated the appearance and extinction of species during 

 geological time. 



A very remarkable paper " On the Miocene Flora of North 

 Greenland," by Professor Oswald Heer (translated by Mr. E. H. Scott) 

 has been published in the Journal of the Koyal Dublin Society. 

 The collection of fossil plants described in the paper was brought 

 from the Arctic regions by Captain Philip H. Colomb, E.N., and 

 Sir Leopold M'Clintock, E.N., and contains 63 recognizable species. 

 It is therefore quite trustworthy as to locality, and sufficiently 

 * Proc. Roy. Soc, No. 90, 1867, p. 372. 



VOL. IV. 2 E 



