^20 Botanical Society of Edinburgh : — 



y In every case I found Diatomacece in the residue, as well as Phyto- 



.fjitharia. Sponge spicules, apparently of freshwater sponges, were 

 less frequent, but occurred in many. In a few cases, where the acid 

 caused effervescence, there was calcareous matter present, but in most, 



^^his was not the case. 



.^ Of course, in those cases in which the proportion of earth was 

 small, the residue consisted chiefly of the insoluble organic matter, 

 through which, however, Diatoms and Phytolitharia were scattered, 



^p greater or smaller proportion. 



^ In the cases where the proportion of earth was larger, the residue 

 was much richer in Diatoms and Phytolitharia, but almost always 

 contained also the dark insoluble organic matter. In several, the 

 proportion of Diatoms in the residue was so large, that it had the 

 appearance of a regular Diatomaceous gathering, after boiling with 

 acids. The most remarkable soils in this respect were one from the 

 Sandwich Islands, one from Lebanon, one from the roots of a German 

 moss, and one from Ailsa Craig. 



It is to be noticed, however, that Diatomacece were found in every 

 case, without exception, and that in all, their proportion to the whole 

 non-calcareous earthy residue was considerable, and often large. In 

 many of those where the proportion of earth was smallest, there was 

 no siliceous matter in the residue, except Diatomacece and Phyto- 

 litharia. 



The soils examined were from various and distant localities ; ther€ 

 were about twenty from the Andes, several from Brazil and other parts 

 of South America, a few from North America, a few from the West 

 Indies, one from the Sandwich Islands, one from New Zealand, a iQSV 

 from India, one from Lebanon, a good many from Germany, some 

 from France, a few from Spain, and some from Britain. 



The great majority of the species of Diatoms in all these were 

 found to coincide with our British forms, but a good many species 

 occurred in the exotic soils which have not yet been found in Britain, 

 and most of these not even in Europe, but which have been figured 

 by Bailey, Ehrenberg, Kutzing, Rabenhorst, &c. 



A good many were observed, which, so far as I know at present, 

 have not yet been figured or described. Lastly, a certain number of 

 species, lately found by Smith, Greville, and others, as well as by 

 myself in Britain, and some of which are scarce, have occurred in 

 these exotic soils. Among these I may name here, Navicula scutel- 

 loideSy W. Sm. (Lebanon), Orthosira spinosa, W. Sm., Grev. (Andes, 

 Germany), Cymbella turgida, W. G. (Sandwich Islands), and Navi^ 

 cula varians, W. G. (various soils). 



Of such species as are unknown to Europe, I shall only mention 

 here Terpsinoe musica^ one of the most striking of known forms, 

 which I found in the first soil I examined, which was from Brazil. 

 It is accompanied by Nitzschia scalaris, a fine form, which occurs in 

 Britain, but is far from frequent here. 



I am satisfied that a close examination of such specimens of soil, 

 which are often thrown away in putting up specimens in herbaria, 

 will bring to light many new forms, and supply us with many exotic 



