HARDWICKE'S SCIENCE-GOSSIP. 



101 



NOTES ON COLLECTING AND PRE- 

 SERVING LAND AND ERESH- WATER 

 SHELLS. 



THERE are two or three little difficulties by 

 which youug collectors are often beset, whicli 

 are not referred to in Mr. Tate's able paper on the 

 above subject. 



It occasionally happens, for instance, after the 

 boiling process has been completed, that from some 

 cause or other (such as an old injury to the shell) 

 the animal, instead of coming out of the shell entire, 

 breaks in two, and the hinder portion is drawn back, 

 and is quite out of sight by the contraction of the 

 part whicli adheres to the shell. I find the follow- 

 ing to be the best plan for getting the remainder of 

 the animal out of a large shell. Take a piece of 

 wire (the kind used for tying soda-water corks 

 answers very well) ; bend the end into as small a 

 hook as possible, and then coil the wire into a sort 

 of spiral spring of such a size that it can be easily 

 screwed, so to speak, into the shell. Introduce the 

 coil as far as possible ; by the backward pressure 

 the connection between the animal and the shell is 

 generally broken. Then withdraw the wire, and it 

 will seldom be necessary to make more than two or 

 three attempts before the little hook catches the 

 remains of the animal and brings them out entire. 

 This mode is not of course available for small and 

 thin shells, but in these the animal generally breaks 

 through the weakness of the tissues, and not from 

 a portion adhering to the shell. To leave the 

 " tail " of the animal, however, in such shells as 

 the transparent species of Zonites greatly disfigures 

 the specimens; but breakage may generally be 

 prevented by drawing the animal out, not in the 

 direction of a tangent to the shell, but round the 

 under side of the outer whorl. By this means the 

 tissues on one side are not stretched more than 

 those on the otlier. To extract the animals of small 

 species, I use a tine-pointed needle fixed in a handle, 

 which I hold like a pencil. 



In order to keep the shells of small bivalves 

 closed until dry, 1 find cotton roving more convenient 

 than thread, as the turns of the roving adhere to 

 one another sufficiently to keep the valves shut 

 without tying. 



Lastly, weathered specimens of land shells are 

 greatly improved by rubbing them over slightly with 

 olive-oil ; after standing a short time every particle 

 of unabsorbed oil should be carefully wiped off. 

 Some shells have a polished epidermis which is liable 

 to crack and flake off when it becomes very dry : 

 a similar application of oil will generally prevent 

 this. G. H. H. 



"The utility of the study ot' natural history will 

 be recognized by any one possessing even rudimen- 

 tary ideas of the icm\CQ:'— Milne-Edwards. 



NEW BOOKS. 



THE inexorable limits of space forbid us devoting 

 more than a few lines to noticing such works 

 of a general scientific character as we think may in- 

 terest and instruct our readers. Never before was 

 the scientific press so active as it is at present, nor 

 do we remember that, on the whole, the work was 

 ever more thoroughly or effectively done. Tiic 

 book to which we draw attention first is a bulky 

 volume, with a " Government " look about it. That 

 soulless body is not obliged to " get up " a work 

 with any view to an attractive appearance, for it is 

 above and beyond all competitors! Thus far, 

 therefore, we would recommend our Government 

 publishers to copy the example of the United 

 States Government, who send forth their works in 

 a manner creditable even to the leaders of the trade. 

 And yet we know of few works more thoroughly 

 useful, or in which there is condensed such a 

 variety of genuine observation and hard work, as 

 the volumes of our own Geological Survey. They 

 literally bristle with facts. Their authors are not 

 allowed that literary liberty which they might 

 assume if " Government " did not interfere. But 

 to those people interested in the almost mathema- 

 tical correctness with which various strata are 

 mapped and measured, with their commoner fossils 

 described, the " Memoirs of the Geological Survey " 

 recommend themselves. The last volum.e issued is 

 on "The Geology of the London Basin," by Wil- 

 liam Whitaker, B.A., E.G.S. ; and this, in our 

 opinion, is by far the most conscientiously and effec- 

 tively compiled of any. Mr. Whitaker's name is 

 well known as that of a most able geologist, and 

 this work of his cannot fail to enhance his repu- 

 tation. In it he has been assisted by Messrs. 

 Hughes, Woodward, Topley, and others. This 

 volume, however, is marked " Part I. The Chalk 

 and Eocene Beds of the Southern and Western 

 Tracts." It therefore includes some of the most 

 interesting stratigraphical phenomena of the later 

 Secondary and earlier Tertiary deposits of this 

 country. The well- sections on the southern and 

 western sides of London are minutely given, a fact 

 that we place on record, on account of its eco- 

 nomical value to well-sinkers and others. The 

 metropolitan and suburban districts are specially 

 particularized, and a section is given of the hypothe- 

 tical ridge of old palseozoic rocks underlying Loudon. 

 A very interesting portion of the volume is that de- 

 voted to geological disturbances and denudation, and 

 the effects of these upon the physical scenery of the 

 district described. A most compendious biblio- 

 graphy, including all the papers and memoirs that 

 have been printed on the geology of the London 

 basin, is given at the end of the work. Altogether, 

 we sincerely congratulate Mr. Whitaker and his 

 colleagues on the successful manner in which 



