GEOLOGY. 291 



with precision the species to which such fragments belong, or at least 

 to get any indication about their mode of vegetation and their rela- 

 tion to plants now living. In the coal, on the contrary, we find a 

 few remains of internal organism, chiefly vessels of various appear- 

 ances. But in the compact, homogeneous matter of the coal, every 

 trace of external structure of the plants having disappeared, these 

 isolated vessels cannot in any way indicate the form of the plant to 

 which they belong. 



It is especially in treating the laminae of mineral charcoal, inter- 

 mixed with compact coal, by chemical maceration, that Professor 

 Dawson has been able to separate the vegetable fibre and to study 

 the form of some of the vessels. The result of these researches is 

 satisfactory to this point : it proves by a direct experiment that the 

 coal is a compound of different species of plants. Though many palae- 

 ontologists had already come to the same conclusions by researches 

 of the same kind, Professor Dawson is the first who has succeeded in 

 clearing the woody fibre perfectly from every particle of amorphous 

 substance, and thus his assertions are more conclusive and more relia- 

 ble. Nevertheless, some of these assertions are open to critical dis- 

 cussion. 



One of the most interesting conclusions reached by Professor Daw- 

 son is that the small cylindrical filaments, resembling black threads, 

 so abundant in the coal, are composed of bundles of scalariform ves- 

 sels inclosed in a sheaf of woody fibres. This is, says the author, pre- 

 cisely the structure of the vascular bundles of tho petioles of ferns. 



The question as to the real character of the Stigmaria ficoides 

 cannot be considered as settled, and it is by no means certain that 

 it is the root of a Sigillaria. 



It is scarcely possible now to refer the genus Sigillaria to Cycadece 

 or to the Conlferce. Neither the internal structure nor what we 

 know of the external forms of species of this genus, the leaves, the 

 fruits, etc., can show such an analogy. Professor Dawson cannot 

 with certainty affirm the presence of tissue of true Conifers in the 

 coal. This agrees perfectly with the results of M. Lesquereux's re- 

 searches, who states that no trace of a coniferous plant has yet been 

 found in the coal measures of the United States. 



In his second paper, Professor Dawson most satisfactorily confirms 

 a former discovery, made by himself and Sir Charles Lyell, of the 

 presence of terrestrial animals in the coal measures of Nova Scotia. 

 In like circumstances, namely, in the hollow petrified trunk of a 

 standing tree, he has found numerous well-preserved specimens of 

 the same land shell, Pupa vetusta Daw., before discovered at the 

 same locality ; some remains of a new genus and species of an articu- 

 lated animal, resembling a Myriapod, and portions of two skeletons 

 of animals belonging to a new reptilian genus, Hylonomus. 



Every geologist will recognize the great importance of this discov- 

 ery, as respects both palaeontology and the history of the coal forma- 

 tions. Discoveries of nearly the same kind as those of Professor 

 Dawson have been made lately both in Europe and in the United 

 States. Goldenberg has found in the coal measures of the Vosges, 

 in France, new species of Blattlnce, Thermites, Dyctloneuron, etc., 



