38 
SILURIAN FOSSILS OF RUSSIA 
and Leptsense, both these genera being completely separated from the Product! 
which are never found in rocks of this high antiquity. Of these fossils twenty 
species are known in the Silurian rocks of the environs of St. Petersburg!^ twelve 
of which belong to Orthis, whilst in the overlying or Devonian system, so full of 
other genera of shells, two species of Orthis and three of Leptama have only been 
discovered (see next chapter, vol. ii., and Table of Organic Remains' 
The Lower Silurian strata of Russia, sti U more than those of are 
distinguished by t ose singular plate-covered bodies of circular forms, with central 
mouths and lateral ova apertures (whereof the Sp^ronUes auran,iu m is the pre- 
vailing type , winch though closely approaching to Crinoidea, well merit to be 
distinguished therefrom. The greater number of these belong to the genera 
Ech, nosphmn.es and Echino-encrini.es of Wahlenberg, but M. von Such, who has 
. rown so much light „„ these fossils, has formed other genera, snob as the 
Hemmosmites To CrVpt0crinil:es ' whicl > as yet have been alone found in Russia 
oils r: t , st r wnte srouped them un<ier ,he <%»«*«. and h as 
0 ose w lie he had previously described, the new genus Svcocystites, 
equally with the others characteristic of the Lower Silurian of Russia, whilst his 
we r nT S s r “ “7 Upl ’ er SilUri “ of G ° th >a"tl only. In the meantime 
we may s ate, that whilst the Cystidem abound in great clusters throughout the 
Lower S, urian beds both of Scandinavia and Russia, they have recently b en 
discovered m strata of the same age in England. They were noticed long ago " 
Sweden by Lmmeus and otner authors, and were distinctly described in a ver, able 
manner by Gyllenhall. The genus Echino-encrinites is also found in Sweden where 
it was for some time confounded with the Echinosphmrites 1 . 
bonites, Terebratula nucella and Lingula longissima. We may add that the very characteristic Spirifer 
hjnx of Russia has its representative in the Atrypa dorsata of Sweden. This Spirifer lynx, whichTT 
common variety of the S. biforatus (Schloth.), has a very wide geographical range, and is one of the 
most abundant fossils in the Lower Silurian beds of North America ; viz. the blue limestone of Kentucky 
I ennessee, Ohio and Indiana. ^ ’ 
1 M. Hermann von Meyer and M. Volborth have also written on the organization of the genus Echino- 
encrinites, and the last of these authors has endeavoured to show that it had true arms around the mouth • 
an opinion from which M. von Bucli entirely dissents. The Echino-encrinus of Von Meyer is the Syco' 
cj states of V on Buch. (See M. von Buch’s last memoir, “ Ueber Cystideen.” Trans. Acad. Berol. 1844 ) 
6 existence ol: Cystidese in England, spoken of in the text, has been made known through the research 
o the Ordnance geological surveyors under Sir Henry T. De la Beche. The fact of the presence of such 
p ° U1 unquestionable Lower Silurian rocks of South Wales, was mentioned to us by Professor 
l ips mi st t lest pages were undergoing their last revise. Fortunately the great authoritv on ft ' 
subject, M. Leopold von Buch, being then on a visit to London, the specimens were submitted to him; and 
