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SCIENCE-GOSSIP. 



GEOLOGY 



The May number of the "Proceedings of the 

 Geologists' Association " (published by Stanford), 

 is well worth reading. It contains Dr. F. Hume's 

 paper on the " Genesis of the Chalk." This is 

 illustrated by a map of the cretaceous ocean in 

 Europe, and by a page of sections representing the 

 variations in thickness of the upper cretaceous 

 zones for some of the principal localities in the 

 British Isles. The paper is well written, full, 

 interesting and suggestive, and should prove useful 

 to those interested in the cretaceous period. The 

 same number also contains Mr. H. B. Woodword's 

 Presidential Address to the Association, delivered 

 in February last, and entitled " Geology in the 

 Field and in the Study," which will be pleasant 

 reading to all interested in geology. 



Somerset Fossils. — In the month of February 

 and March I collected from the Middle Lias 

 round South Petherton and Ilminster the 

 following fossils of Cephalopoda : Ammonites 

 communis, A. planorbis, A. varians, Belemnites 

 mucronatus ; of the Lamellibranchiata, Unio 

 and Anodonta, and Pecten beaveri ; of the 

 Brachiopoda, Rhynconella, which was exceedingly 

 plentiful. From the cretaceous formation, which 

 crops out on a spur of the Blackdown Hills, near 

 Chard, where a fine section of the chalk can be 

 seen, I collected of the Echinoderms, Micraster 

 cor-anguinum, and Tcnechinus excavatus ; of the 

 Cephalopoda, Ammonites varians and Nautilus dancei ; 

 of the Lamellibranchiata, Plagiostoma oUiqua and 

 Pecten. — Rev. A . C. Denman, Fivehead, Taunton, 

 Somerset ; April n, 1894. 



"Natural Science" for this month has an inter- 

 esting article on the question "Can the sexes in 

 Ammonites be distinguished ? " Many well-known 

 palaeontologists have maintained that secondary 

 sexual characters are manifested in the shells of 

 the Cephalopoda, and that many forms now 

 bearing different specific names are really only 

 male and female of the same species. Those of 

 our readers who are interested in Ammonites are 

 referred to the conclusion arrived at by Messrs. 

 Buckman and Bather. After a careful examination 

 of the evidence on this point, we give it in their 

 own words: "We suggest that the characters in 

 question are auxologic or bioplastic rather than 

 sexual, being in some cases phylogerontic, in others 

 merely ephebic or gerontic, and we conclude that 

 sexual dimorphism has yet to be proved for 

 Ammonite shells." 



Bristol Geologists' Association. — We are 

 indebted to Mr. Frederick Ellis for information 

 respecting this newly-formed society, of which he 

 is the Honorary Secretary. The Association has 

 been in existence about six months and has a 

 membership of eighteen. It aims at meeting a 

 want, inasmuch as it is the first geological society 

 formed in Bristol, although there is a section 

 devoted to geology in the Bristol Naturalists' 



Society. The distinctive features of the Associa- 

 tion appear to be a small subscription (is. per 

 annum), Sunday meetings and frequent excursions 

 on the same day of the week. The summer 

 programme shows that two excursions per month 

 is the rule from May to October inclusive. 

 There have also been meetings held at the houses 

 of members for the reading of papers, the exhibi- 

 tion of specimens and the study of text-books. 

 The members would be pleased to afford 

 information respecting local rocks and fossils to 

 any fellow readers of Science-Gossip, on com- 

 munication with the Honorary Secretary, whose 

 address is 22, Senier Street, Bristol. 



The Limbs of Trilobites. — In the June number 

 of the ' ' Geological Magazine' ' there appears a further 

 contribution, under the heading "Woodwardian 

 Museum Notes," upon the Fossil Trilobitidae, and 

 Mr. Chas. D. Walcott also has an interesting paper 

 upon the recently-discovered locomotive organs of 

 the same animals. The limbs are arranged in 

 pairs at intervals along the sides of the body. 

 They are many jointed and in some cases provided 

 with supernumary appendages in the shape of 

 bristles, basally jointed and fringed apically. The 

 number and arrangement of these limbs serve to 

 connect the trilobites more closely than ever with 

 the Crustacea. 



Geology and the Relief of the Globe. — 

 This was the title of a remarkable lecture 

 delivered by Professor Lapworth to the Geologists' 

 Association, on the 1st June. The lecture was 

 substantially the same as one he had read before 

 the Geographical Society a few weeks previously, 

 and in whose "Proceedings" it will probably be 

 reprinted. The object of the lecture was to find 

 some unit in the varied relief of the globe, which 

 would correspond to the species of biological 

 classification ; and, further, if such a unit could be 

 found, to trace the laws regulating its associations 

 and arrangement, whereby the relief of the globe 

 is caused. The lecturer skilfully laid before his 

 hearers the reasons by which he had been led to 

 the conclusion that a simple undulation was the 

 unit underlying the physical features of the earth's 

 surface. He then proceeded to show that the 

 distribution of land and water may be very closely 

 reproduced by a membrane resting on water, which 

 is caused to vibrate along six lines, three at right 

 angles to the other three. The positions of the 

 parts of the vibrating membrane above and below 

 the surface of the water then corresponds to the 

 positions of the continents and ocean basins of the 

 globe. The lecturer, however, did not rest here, 

 but showed how the same law held good when 

 applied to Schiaparelli's map of Mars. Again, he 

 traced it through the whole geological history of 

 the British Isles. By drawing a line of time, and 

 marking off along it the oscillations of this part of 

 the earth's crust during each of the geological 

 formations, a remarkable similarity of curves was 

 obtained. We believe we did not misunderstand 

 the Professor's remark that " These things are not 

 so because the earth is a contracting sphere, but 

 because they are in the nature of things." Prof. 

 Lapworth's method of approaching the subject was 

 a strictly logical and scientific one, and if his 

 views will stand the test of closer examination and 

 study, geology will have entered on a new era of 

 its history, and a new path to knowledge will have 

 been opened up, leading to far-reaching results 

 whose importance cannot be overestimated. 



