io6 



HARDWICKE'S SCIENCE-GOSSIP. 



extinct as a British species. It has been found fossil 

 in various parts of England as well as on the Continent. 

 In searching over my treasures a short time ago, I 

 came across a box containing a small quantity of a 

 curious deposit containing freshwater shells, which 

 was given to me by Mr. Storrie, the curator of the 

 Cardiff Museum, in 1 888. The deposit which was 

 found eighteen feet below the surface in the excava- 

 tions for Barry Dock, near Cardiff, contains numerous 

 shells of Limnaa peregra, as well as a number of 

 spiral shells which much resemble H. ventrosa, and 

 which undoubtedly is that species. 



In conclusion, I should like to add that, should our 

 Plumstead-Beckton species prove to be quite un- 

 known to conchologists, it will be rather interesting 

 to try and discover from whence it originated. If it 

 is an introduced species, where did it originally come 

 from, and by what means ? We have ample proofs 

 that several of our British shells have been introduced, 

 and have adapted themselves to our varying climate. 

 Dreissina polymorpha, which was introduced here 

 from America, has flourished so as to prove rather 

 a nuisance in our canals and rivers, and Bulimas 

 Goodallii, which was originally brought over from 

 Guadaloupe in 1822, has since that time spread from 

 greenhouse to greenhouse, in various parts of England. 



The illustrations, which were taken from my own 

 specimens, are enlarged about two diameters for 

 the shells, and four diameters for those representing 

 the animals as they appear when crawling. 



New Cross. 



A DEEP CHANNEL OF DRIFT IN THE 

 VALLEY OF THE CAM, ESSEX. 



AVERY interesting paper was recently [read 

 before the Geological Society on the above 

 subject by W. Whitaker, Esq., B.A., F.R.S., 

 F.G.S. In Scotland and in northern England long 

 and deep channels filled with drift have been 

 noticed, but not in southern England. For some 

 years one deep well-section has been known which 

 showed a most unexpected thickness of glacial drift 

 in the higher part of the valley of the Cam, where 

 that drift occurs mostly on the higher grounds 

 and is of no very great thickness. Lately, further 

 evidence has come to hand, showing that the 

 occurrence in question is not confined to one spot, 

 but extends for some miles. The beds found are for 

 the most part loamy or clayey. At the head of the 

 valley various wells at Quendon and Ridding show 

 irregularities in the thickness of the drift, the chalk 

 coming to or near the surface in some places, whilst 

 it is nearly 100 feet below it sometimes. Further 

 north, at Newport, we have the greatest thickness of 

 drift hitherto recorded in the south of England, and 

 then without reaching the base. At one spot a well- 

 reached chalk at 75 feet ; whilst about 150 feet off 

 that rock crops out, showing a slope of the chalk- 



surface of 1 in 2. In the most interesting of all the 

 wells, after boring to the depth of 340 feet, the work 

 was abandoned without reaching the chalk, the drift 

 in this case reaching to a depth of about 140 feet 

 below the level of the sea, though the place is far 

 inland. The chalk crops out about 1 000 feet 

 eastward, and at but little lower level, so that there 

 is a fall of about 1 in 3 over a long distance. At and 

 near Wenden the abrupt way in which drift comes 

 on against chalk has been seen in open sections- 

 Two wells have shown a thickness of 210 and 296 

 feet of drift respectively ; and as the chalk comes 

 to the surface, at a level certainly not lower, only 

 140 yards from the latter, the chalk-surface must 

 have a slope of 1 in less than I J, and this surface 

 must rise again on the other side, as the chalk again 

 crops out. The drift here reaches to a depth of 60 or 

 70 feet below the sea-level. At Littlebury, in the 

 centre of the village, a boring 218 feet deep has not 

 pierced through the drift, which reaches to 60 feet 

 below the sea-level. As in a well only 60 yards west 

 and slightly higher, the chalk was touched at 6 feet, 

 there must here be a fall of the chalk-surface of about 

 1*2 in 1. Eastward, too, on the other side of the 

 valley, the chalk rises to the surface. The places 

 that have been mentioned range over a distance of 

 6 miles. How much further the drift-channel may 

 go is not known, neither can we say to what steep- 

 ness the slope of the underground chalk-surface may 

 reach ; the slopes given in each case are the lowest 

 possible. Mr. Whitaker thinks that the channel has 

 been formed by erosion rather than by disturbance or 

 dissolution of the chalk. 



ILLUSTRATIONS OF VEGETABLE 

 TERATOLOGY. 



THERE is nothing more suggestive to a botanist 

 than the singular floral shapes which members 

 of the same orders of plants run into. Geologists 

 cannot tell with precision the exact period when 

 gaily coloured flowers came into existence. We can 

 trace back many wind -fertilised plants, such as oak, 

 maple, etc., to the lower cretaceous period. Prac- 

 tically, all the existing orders of insect-fertilised,, 

 and therefore beautifully coloured, adorned, and 

 perfumed flowers have well evolved during the 

 tertiary period. The degree of evolution has 

 probably proceeded from polypetalous to gamo- 

 petalous types of flowers; and from regular gamo- 

 petalous to irregular kinds. Thus, "sports" may 

 sometimes be a kind of spurting onward, although 

 they are more frequently reversions to older stages 

 of floral development. 



Take the order Scrophulariacere, for example. It 

 includes flowers like those of the Speedwells, whose 

 four petals are only just united together. It seems as 

 if the slightest change would take them back to a 



