xxviii FACTS AND OBSERVATIONS. 



elsewhere in the Upper Llandovery, or higher ; England therefore appears to be its birth-place ; 

 Conocardium, sp. ind., may be French, but we wait for more information ; Ribeiria pholadiformis is in 

 Caradoc in Portugal, but it is in D. d. 1, still lower down, at Vosek and Zahorzan in Bohemia, where, 

 therefore, we place the first appearance of this species of Dimyaria. 



Hetero-Pteropoda. Of the thirty-eight species in Bohemia, by far the majority are natives. 

 In the rare instances where the same species is found in other regions, the stratal zone is the same, 

 as in the cases of Betterophon acutus, B. bilobatus, B. trilobatus, and Theca simplex. The first three 

 of the above species show themselves in so many and such distinct countries, that we feel inclined 

 to explain the facts by the notion of multiple creations. 



Gasteropoda. Of the fifty-one Silurian genera of this order, Bohemia contains twenty-two, in 

 245 species ; but only the five inserted in the footnote are met with in other parts of the world t, 

 and of these the two species of Acroculia only seem to be foreigners. 



The positive rarity of Mollusca under any form coming from other regions is a very strong 

 indication of the Prague basin being with difficulty accessible from without, except on a few 

 remarkable occasions. In the bays and sounds of the present seas the Mollusca change but little, 

 and are peculiar. 



Cephalopoda. It is a singular fact that Bohemia contains more than half of all the known 

 Orthoceratites (396 out of 696), nearly all the species being typical of that country. 



Thirty Cephalopoda have relations with other regions. Nine Bohemian Orthoceratites originate 

 in Spain, France, Britain, and Ireland J, in the extreme west of Europe, where they are in the 

 Caradoc and its equivalent stages, while they are in the third fauna in Bohemia ; three of these 

 (marked *) are also in the Lower Silurian of Russia and Norway. Six Orthoceratites, in the 

 same way, are derived from the North and N.N.W. that is, from Russia and Norway. 



Orthoceras pelagicum is both in France and Bohemia, and probably on the same horizon, like 

 Bactrites nanus, Cyrtoceras Iceve ?, 0. bullatum ?. 



Orthoceras dulce (Sweden, Britain), 0. originate (Britain), O. styloideum (France, Thuring.), 

 O. tumidum (Ireland), are native Bohemian species, together with the great body of this order in 

 that basin. We add a few words on this order. 



The Goniatites of De Haen (having their maximum in quantity &c. in the Devonian epoch), 

 seventeen in number, abound in many parts of the environs of Prague, especially at Hlubocep, 

 making their first appearance as low down as F. f. 2. 



It is probably in the little contiguous parishes of Lochkov and Kozorz, a few miles west of 

 Prague, that the crowd of Orthoceratites is the greatest. Seventy-one species, each consisting of 

 individuals past enumeration, are in Lochkov, overflowing into Kozorz ; and forty-three species, 

 mostly distinct, are in Kozorz. There are thirty-two species at Dvoretz, nearer Prague, almost all 

 peculiar to Dvoretz. Further inquiry would, I know, show something like the same state of things 

 in other parts of this Silurian deposit. 



This genus is also remarkable in its vertical distribution. It makes 345 appearances in Bohemia 

 (with others elsewhere) . There are none in the Primordial stage (Fauna C) ; but in D we find 24 ; 

 in E. e. 1, 52 ; in E. e. 2, 203 ; in F, 22 ; in G, 40 ; in H, 4. Here we remark scantiness at the top 

 and bottom, with an extraordinary opulence in E. e. 2, a limestone m4a*e--erHhgss~CpnnGotod~-with 

 trappose rooks, as in the British Gasteropoda. 



Recurrence is common; it occurs in 126 species, and especially from Fauna E to Fauna G. 

 t Acroculia haliotis, Sowerby, (Llan.) Scotland, (Upper Silurian) Bohemia ; A. rostrate, Eichwald, (Pleta) Baltic 

 Russia, (Faunae F, G) Bohemia ; Euomphalus monoplectus, E. substriatum, E. trochleatum, Bohemia and Franconia 

 (Upper Silurian). 



| Orthoceras ibex *, 0. calamiteum, O. irregulare, 0. gregarium, O. lineare *, O. Ludense *, 0. nummularium, 

 O. subannulare, O. tenuicinctum. 



Orthoceras distans , 0. annulatum, 0. Ibex, 0. Ludense, 0. regulare, O. lineare. 



