THE FLORA OF THE COAL FORMATION. 495 



and a better view of the general arrangement of the tissues than can 

 be obtained from the shreds of woody matter resulting from the process 

 above described. 



It is further necessary to state that, to compare specimens of coal 

 with the structures of mineralized plants from the accompanying beds, 

 it is not sufficient to have slices of the latter. It is necessary also to 

 have specimens prepared by removing the mineral matter by an acid. 

 Most of the coal fossils showing structure are mineralized by tlie car- 

 bonates of lime and iron ; and on removing these, the cell-walls will 

 be found intact and sometimes apparently not even carbonized. Diluted 

 hydrochloric acid suffices for this ; and structures by no means to be 

 found in the comparatively rude slices prepared by the lapidary can 

 be distinguished in these isolated cells. Pyritous fossils, so intractable 

 as slices, can usually be resolved by the treatment with nitric acid, 

 though in some cases they require a preliminary roasting, or, what is 

 better, exposure to the weather until the pyrites begins to crumble. 



The observer using the above method will find many vegetable 

 fibres showing no markings. These are usually bast fibres. He will 

 see others with one row of round pores (uniporous), or with distant 

 round pores scattered irregularly (rariporous), or with several rows of 

 alternate simple or bordered pores (multiporous). These are tissues 

 of Sigillaria and Calamodendron^ except some large vessels of the 

 last mentioned type, which belong to Calamites. With the porous 

 tissues he will often find slender scalariform vessels, or rather cells with 

 transverse pores, which also belong to Sigillaria and Calamodendron, 

 and are very different from the large coarse scalariform vessels of 

 Lepidodendron and its allies, and of Stigmaria. The ducts of ferns 

 have been already referred to. Some of these varieties of mineral 

 charcoal afford very beautiful microscopic objects. 



Note on the Myriapods of the Coal Formation. 



The following has been communicated to me by IVIi* Scuddei', since 

 the printing of the notice of these creatures at page 385, supra : — 



"The specimens of Myriapods discovered by Dr Dawson in the 

 Sigillarian stumps of the Coal formation of Nova Scotia, belong to 

 two genera ; in one, Xyluhius^ Daw., cross sutures divide the seg- 

 ments into numerous fragments, in a maimer wholly unknown among 

 living Myriapoda ; in the other, which we may call ArchiiduSy the 

 segments are simple. Of the former genus, I have discovered no 

 less than four species among the fragments which Dr Dawson has 

 permitted me to examine. For one the name of X. sigillaria', Daw., 

 may be retained; the illustrations (Fig. 151, a, o, p. 385) probably 



