224 



NA TURE 



[July 5) 1883 



The only corrective of immoral publications of this 

 description is to be found in reproducing them before 

 public opinion of another kind from that of the unfor- 

 tunates whose eyes alone they are intended to meet ; and 

 it is partly this consideration that has led us to review 

 Mr. Yorke's essay, which, although excellent in itself, is 

 hardly in close enough contact with natural science to 

 demand notice in these pages. 



George J. Romanes 



OUR BOOK SHELF 



Iconographie der schalentragenden curopiiischen Meeres- 

 conchylien. Von Dr. W. kobelt. 4to. Hefti. (Cassel : 

 Theodor Fischer, 1883.) 



The object of this work is to supply a want which is con- 

 tinually felt by conchologists, and it deserves the greatest 

 success. Dr. Kobelt is well known to science as the 

 editor of the Jahrbucher and Nachrichtsblatt der deulschcn 

 Malakozoologischen Gesellschaft, which has now been 

 published for between fifteen and sixteen years, and as one 

 of the editors of the new Conchylien-Cabinet of Martini 

 and Chemnitz ; and he is also the author of several works 

 and papers on conchological subjects. It appears from 

 the prospectus of the present work that its scope will be 

 confined to the coasts of Europe, including the English 

 Isles, the Faroes, and Scotland, and bounded by the 

 north coast of Africa, but excluding not only tropical and 

 subtropical species of Mollusca, but those Arctic species 

 from Spitzbergen and the north of Iceland which are not 

 found on the coasts of Upper Norway. This scope, 

 although extensive, is not very definite ; and it scarcely 

 accords with our usual notion of the European seas. We 

 do not know what may be the author's limit of depth, 

 whether it is the line of soundings or 100 fathoms ; nor 

 whet'ier he will even take the Mollusca now about to be 

 published from the Triton cruise between the Faroes and 

 Scotland. The expeditions of the Josephine, Lightning, 

 Porcupine, Challenger, Vbringcn, Travailleur, Washing- 

 ton, Knight Errant, and several others, have of late years 

 done much to aid in the exploration of the European seas 

 at various depths ; and the number of species thereby 

 added to the Mollusca has been very considerable and is 

 still increasing. Some additions have likewise been made 

 from time to time to the Mediterranean Mollusca, espe- 

 cially by myself during the present month. Taking into 

 account all these discoveries, I am inclined to reckon the 

 number of species hitherto described as inhabiting the 

 littoral zone and moderate depths in the European seas 

 as not less than 1000; probably 1200 would be nearer 

 the mark. 



The first part of the present work, which has now ap- 

 peared, gives figures of four species only and their 

 varieties, one of which species [Murex gibbosus) is 

 Senegalese, and has never (to the best of my knowledge 

 and belief) been found in any part of the European 

 seas. This reduces the number of figured species 

 to 3. Perhaps the species will not be so profusely 

 illustrated in the next and following parts. The pub- 

 lished prospectus does not give any idea of the extent 

 of the work. But assuming even that twenty species 

 (large and small) may on an average be figured in each 

 part, the entire work would take not less than from fifty 

 to sixty parts, and would cost for an uncoloured copy 10/. 

 to 12/., and for a coloured copy 15/. to 18/. If all the 

 species known to inhabit the European seas, including the 

 abyssal and benthal zones, are to be figured — and I think 

 this ought to be done — the extent and cost of the publica- 

 tion must be increased by probably a fourth more. 



However, such calculations have doubtless been con- 

 sidered by the author or his publisher. The work will 

 assuredly be far more scientific and valuable than the 



very irregular but expensive Conchologia Iconica of the 

 late Mr. Reeve, and be not merely an "ouvrage de luxe." 

 The family Muricidee, which is the first selected for 

 publication, does not seem to be placed in the usual order 

 of classification. All the figures are admirable. The 

 descriptions are in Latin, the text in German. The 

 geographical, hydrographical, and geological distribution, 

 as well as the odontophore and synonymy, are carefully 

 worked out. J. Gwyn Jeffreys 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts, 

 No notice is taken of anonymous communications. 



[ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible otherwise to insure the appearance even 

 of communications containing interesting and novel facts.] 



Sand 



I have recently been favoured with a reprint of Mr. J. G. 

 Waller's paper upon sand, read before the Quekett Micro- 

 scopical Society. The subject is so full of intere-t that I trust 

 I may be allowed to give it a wider publicity in your columns. 

 To render the study of practical use to geologists and physicists, 

 the first step appears to me to ascertain whether it is pjssible to 

 distinguish with certainty, by aid of the microscope, sand that 

 has been worn by action of wind from sand that has been for 

 long exposed to surf, and this again from sand brought down by 

 torrents. The degree of rounding and the average size of the 

 grains would be, I presume, among the chief characteristics, and 

 it is to be hoped that naturalists abroad will kindly forward 

 examples of undoubted blown and torrential sand, so that this 

 point at least may be settled. 



If it should prove that the origin of sand can be pronounced 

 upon with any degree of certainty, from a microscopical exa- 

 mination, we should ome into possession of a most valuable aid 

 to fie stvidy of at least Tertiary geology. It is well known that 

 marine and freshwater deposits succeed each other repeatedly 

 throughout our Eocene formations, and where deposits of sand 

 are in juxtaposition, it is at present impossible to draw any line 

 between them. It is only possible to surmi-e that they are of 

 different origin arid therefore age, when pebble or oyster beds 

 on the one hand, or films of clay with plant impressions on the 

 other, are accidentally included in them. So far as our own 

 Eocenes go, it appears from Mr. Waller's results that their 

 sinds, when of marine origin, possess a percentage of flint 

 grains, but that purely fluviatile sands do not possess any. 

 Marine and fre-hwater sands are in direct contact in very 

 many of our Eocene sections, and I hope Mr. Waller's researches 

 will enable us to distinguish them and apportion the proper 

 thickness to each. 



With regard to the relative rarity of flint-grains and pre- 

 ponderance of quartz, in all the Tertiary and recent sands hither- 

 to examined, it appears just possible that the concussion the 

 flint grains mu t undergo when beaten for ages in the surf, might 

 induce a molecular change from the colloid to crystalline state, 

 but in the absence of any fact or argument to support such a 

 theory it cannot be seriously entertained. It is however pos- 

 sible that quartz grains reach a final state of subdivision, and 

 then suffer relatively little by attrition, and are therefore almost 

 indestructible, while flint grains become rapidly degraded into 

 mud. 1 his appears to be very much the opinion Mr. Waller 

 has formed. It does seem at fir.-t sight matter for surprise that 

 the grinding of flint should n it more largely affect the composi- 

 tion of our sea sand ; but we must on the other hand reflect on 

 the indestructible nature of the quartz grains that chiefly com- 

 pose it, that it may have been accumulating since palaeozoic times, 

 and the enormous bulk of the quartzose rocks that mu.t have been 

 ground down to supply it during such vast ages, and then com- 

 pare tbe sources with flints which in comparison only appeared 

 yesterday, and then but as scattered segregations in a limited 

 portion of a single formation. Flints and flint beaches, 

 recent and ancient, are at our gates, and are continuously re- 

 newed by the wearing away of the chalk of which so much 01 

 our part of England is composed, and their aggregate mass 

 therefore astounds us ; but they after all occur over only a 



