HARDWICKE'S SCIENCE GOSSIP. 



209 



the distribution of plants would, in all probability, 

 be far easier to trace among the perennial orders of 

 cryptogams, such as mosses and lichens, than among 

 flowering plants. The occurrence of the fungi and 

 fresh-water algse is, no doubt, governed more by 

 accidental circumstances, such as the presence of 

 the soil, and meteorological conditions necessary for 

 their development, than by geographical position, 

 but the mosses and lichens exhibit very marked 

 uniformities of distribution in horizontal and vertical 

 space. Tohjtrichm sexmgulare, for instance, may 

 readily be referred to the Highland, Thyscia flavi- 

 cans to the English, and many of the Jungermannise 

 to the Atlantic type of distribution. Moreover it 

 would be comparatively rare among the lower 

 cryptogamia to find introduced species— aliens and 

 casuals -and extinctions are hardly likely to occur. 

 The objection which has been raised to the object of 

 the Botanical Locality Record Club, as tending to 

 the eradication of rare species by unscrupulous 

 collectors, would not apply here, for mosses, lichens, 

 algce, and fungi are not likely ever to become a 

 fashionable mania among the class of collectors 

 whose destructive greed threatens to render a fern 

 a thing of the past. I am aware that there are 

 many difficulties in the way of the proposed exten- 

 sion, but none I would hope insuperable. It may 

 be said that it would increase at least fivefold the 

 already, I fear, arduous duties of the able recorder, 

 that it would be too much to expect that any one 

 botanist should have a critical knowledge of the 

 species of every order. These difficulties might be 

 readily surmounted by constituting each of the great 

 orders of cryptogamia a special department under 

 the care of a separate recorder. It may also be 

 said that there is no standard catalogue of species 

 to work by, like the London Catalogue of flowering 

 plants; but the Rev. J. M. Crombie has published 

 a catalogue of lichens, and Dr. M. C Cooke one of 

 fungi; and if the Botauical Society Record Club 

 could bring about the compilation of similar cata- 

 logues for the other orders, it would render no mean 

 service to British botany. Again, it may be ob- 

 jected that the harvest truly is plenteous, but the 

 labourers are few. Perhaps so ; but the students of 

 cryptogamic botany are becoming yearly more 

 -numerous, and there can be little doubt that the 

 prospect of being able to add a few stones to the 

 temple of Elora would induce many to take up this 

 branch of botanical science, or, having taken it up, 

 to pursue it with fresh vigour. I for enc shall be 

 ready to add my mite to the general stock of 

 knowledge.— H. F. Parsons, Goole. 



GEOLOGY. 



Swiss and Italian Eloba.— A correspondent, 

 " C. E. T.,"Lwishes to know the best works on 

 Italian and Swiss plants. Perhaps some of our 

 botanical readers will answer the query, and, if 

 possible, state the prices and publishers. 



" The Probable Physical Conditions under 

 which the Cambrian and Lower Silurian 

 Rocks were Deposited over the European 

 Area."— This is the title of a paper read by Henry 

 Hicks, Esq., F.G.S., before the Geological Society 

 of London. The author indicates that the base 

 line of the Cambrian rocks is seen everywhere in 

 Europe to rest unconformably upon rocks supposed 

 to be of the age of the Laurentian of Canada, and 

 that the existence of these Pre-Cambrian rocks 

 indicates that large continental areas existed pre- 

 vious to the deposition of the Cambrian rocks. The 

 central line of the Pre-Cambrian European continent 

 would be shown by a line drawn from S.W. to N.E., 

 along the south coast of the English Channel, and 

 continued through Holland and Denmark to the 

 Baltic. Its boundaries were mountainous; they 

 are indicated in the north by the Pre-Cambriau 

 ridges in Pembrokeshire, in the Hebrides and 

 Western Highlands, and by the gneissic rocks of 

 Norway, Sweden, and Lapland. The southern line 

 commenced to the south of Spain, passed along 

 Southern Europe, and terminated probably in some 

 elevated plains in Russia. Between these chains 

 the land formed an undulating plain, sloping 

 gradually to the S.W., its boundary in this direction 

 being probably a line drawn from Spain to a point 

 beyond the British Isles, now marked by the 100- 

 faUiom line. The land here facing the Atlantic 

 Ocean would be lowest, and would be first sub- 

 merged, when the slow and regular depression of 

 the Pre-Cambriau land took place. The author 

 points out that the evidence furnished by the Cam- 

 brian and Lower Silurian deposits of Europe is in 

 accordance with this hypothesis. In England they 

 attain a thickness of 23,000 to 30,000 ft.; in Sweden 

 not more than 1,000 ft.; and in Russia they are 

 still thinner, and the earlier deposits seem to be 

 wanting. In Bohemia they occupy an intermediate 

 position as to thickness and order of deposition. 

 The author discusses the phenomena presented by 

 the Welsh deposits of Cambrian and Lower Silurian 

 age, and shows that we have first conglomerates 

 composed of pebbles of the Pre-Cambrian rocks, 

 indicating beach conditions, then ripple- marked 

 sandstones and shallow-water accumulations, and 

 then, after the rather sudden occurrence of a greater 

 depression, finer deposits containing the earliest 

 organisms of this region, which he believes to have 

 immigrated from the deep water of the ocean lying 

 to the S.W. After this the depression was very 

 gradual for a long period, and the deposits were 

 generally formed in shallow water ; then came a 

 greater depression, marked by Gner beds containing 

 the second fauna; then a period of gradual sub- 

 sidence, followed by a more decided depression of 



