XXXVI 



FACTS AND OBSERVATIONS. 



when species are common to two sets of beds more or less apart, the connexion between the latter 

 is closer than has been hitherto thought, and, further, that the absence of identical species in the 

 two beds does not forbid considerable relationship. Edward Forbes goes further, and says that a 

 large proportion of all known species of fossils are founded on a single specimen, &c. (Proc. 

 Geol. Soc. Lond. vii. 52). It certainly seems that there was considerable stagnation of move- 

 ment in those times a great arrest, cosmic, because universal. 



Multiple creation is implied, going on everywhere, and affecting every form of life. The grand 

 mystery of creation has been in operation all through the epoch in thousands of places. Ordinarily 

 the Crinoid and the Cephalopod found graves in argillaceous limestone, the Lamellibranchiate in a 

 mixed sandy mud, and so on. 



When we find a species only in one set of conditions, we obtain but a partial acquaintance with 

 its habits and modifications ; we appear to be only at the beginning of our work. 



By way of bringing these facts before the reader in some little detail, the following Table 

 (S) has been prepared. 



Compared with the totals given in p. vii, it will be seen that in each order the tendency of 

 the species inhabiting only one place is to one-half of the whole number. The Trilobita, Bra- 

 chiopoda, Gasteropoda, and others fall short of it ; while Crinoidea and Entomostraca (as might 

 be expected), together with Dimyaria, are all three in excess of their respective moieties. All the 

 species of Pisces and incertee sedis belong each to one separate place. 



TABLE S. Exhibiting the number of Silurian species known only in one place. 



We will proceed to mention a few of the more striking facts connected with locality. 



Silurian fish are only spoken of as existing in Bohemia, Britain, Russia, and the State of New 

 York ; but they must be in other countries. 



Out of our sixty species of the genus Asaphus, only one is known in Bohemia and no Olenus, 

 a large genus elsewhere. The genus Dikelocephalus (Trilobita) contains thirty species, but only 

 three exist in two areas ; twelve are near Quebec, and there only ; nine others are in Minnesota ; 

 and Texas with Vermont have each one, all distinct species. 



Each of the twenty-seven known species of Maclurea is confined to one spot. Twenty are 

 American only; and of these, eleven are seen on the western coast of Newfoundland, and principally 

 at Point Rich. 



Together with many members of other orders, at least 112 species of the genus Cyrtoceras, 

 twenty-seven of the genus Trochoceras, and thirty species of Orthoceras are huddled together in the 

 adjoining little parishes of Lochkov and Kozorz, near Prague. As with the many other Mollusca 

 placed there, these species are unknown elsewhere ; migration seems to have been impossible. 



Most of the Bohemian Brachiopoda are in the rocks around Konieprus and Mnienian, and are 

 peculiar to them. Out of the general body of the Orthides, numbering 331 species, only two are 

 supposed to be in Nova Scotia. Of the 132 species of Murchisonia, again, but two species are 

 there, and not one of the 171 species of Pleurotomaria, a conspicuous shell. On the other hand, 

 Nova Scotia holds one half of the genus Cleidophorus, and Tasmania is singularly rich in the 



