December 21, 1899] 



NATURE 



19] 



Geological Society, December 6.— W. Whitaker, F.R.S., 

 President, in the chair.— Dr. Blanford described certain photo- 

 graphs sent by Mr. E. H. L. Schwarz, and representing the Dwyka 

 boulder-bed and the rounded and grooved^underlying surface, in the 

 neighbourhood of the Orange River near Hopetown and Prieska. 

 The importance of these photographs lay in the evidence which 

 they afibrded on a disputed point. Dr, Sutherland and Mr. 

 driesbach had called attention to the evidence of ice-action pre- 

 sented by the Dwyka Conglomerate in Natal, and additional 

 evidence had been brought forward by several observers, 

 especially by Mr. Dunn from the Orange Free State and Cape 

 Colony, and recently by Dr. Molengraaff from the Transvaal. 

 Other observers, however, and especially the late Prof. Green, 

 had disputed the glacial origin of the Dwyka beds. The 

 photographs now exhibited would, the speaker thought, con- 

 vince most geologists that the phenomena presented were due 

 to ice-action. The resemblance to similar photographs shown 

 to the Society in 1896 by Prof. T. VV. Edgworth David, and 

 representing the beds corresponding to the Dwyka Conglomerate 

 in South Australia, was noteworthy. Evidence of glacial action 

 in Upper Palaeozoic times had gradually accumulated from 

 India, Australia, and South Africa, and there was a probability 

 that similar indications existed in South America. — On the 

 geology and fossil corals and echinids of Somaliland, by Dr. J. 

 W. Gregory. British Somaliland consists of a high plateau, of 

 which the northern scarp is separated from the Gulf of Aden by 

 " a belt of low hills and plains known as the Guban. The 

 southern plateau consists of Archaean gneisses, quartzites, 

 amphibolite-schists, chloritic .schists, and pegmatites. It is 

 capped by purple grits, red sandstones, and conglomerates, 

 which are covered by limestones of Neocomian, Turonian 

 (PCenomanian), and Eocene ages. The Neocomian limestone, 

 which may be correlated with that of Singeli described by 

 Rochebrune, occurs at Dobar in the Guban ; while a Jurassic 

 limestone, probably of Bathonian date, occurs at Bihendula in 

 the Guban. Fossils collected from these limestones and from 

 raised reefs of Pleistocene age, have been examined by the 

 author, who tabulates a list of corals and echinids. The 

 evidence of the collections is sufficient to show that a Neo- 

 comian limestone occurs both on the summit of the Somali 

 plateau and on the floor of the Guban, and that some marine 

 limestones of Lower Tertiary age (probably Eocene) also occur on 

 the plateau. It is therefore evident that the foundering of the 

 Aden Gulf is post-Eocene in age — Note on drift-gravels at West 

 Wickham (Kent), by George Clinch. The author describes two 

 beds of drift-gravel at West Wickham. The first, occupying the 

 bottom of a dry valley, yields in a section exposed at Gates 

 Green, material derived from the Chalk and the Lower Green- 

 sand ; and distinct, although perhaps not direct, relation with 

 the denudation of the Weald is claimed for it. The other bed 

 of gravel is of later age, and has yielded many Paleolithic 

 implements and flakes. — On the occurrence in British carbon- 

 iferous rocks of the Devonian Genus Palaeoineilo, with a de- 

 scription of a new species, by Dr. Wheelton Hind. The family 

 Nuculidse is represented in carboniferous rocks by the genera 

 Nticula, Nuitilana, and Ctenodonta, and to these must now be 

 added Palaeoneilo, which the author describes from two fine 

 specimens in the Museum of Practical Geology, from carbon- 

 iferous shale (Voredale Shale) south of Hammerton Hall, Slaid- 

 burn, Yorkshire. It is remarkable that a genus so well developed 

 in Devonian times should be found at the top of the carboniferous 

 limestone series, but not in intermediate beds. Hall's diagnosis 

 of the genus is given, with additional remarks, and a new 

 species is described and contrasted with Ctenodonta {Palaeoneilo) 

 lirata, Phil., from the Devonian of Baggy. 



Entomological Society, December 6.— Mr. G. H. Verrall, 

 1 'resident, in the chair.— Mr. J. J. Walker exhibited a specimen 

 of Colias marnoana, Rogenh., taken at Massowah, on the Red 

 Sea. He considered this form to be only a dwarfed race of 

 C. hyale, Linn. ; and for comparison with it, he showed speci- 

 mens of the var. nilgherriensis, Feld., from Central India, and 

 of the var. simoda, De L'Orza, from Japan.— Dr. Chapman 

 exhibited a series of specimens, selected from various English 

 collections, together with a few foreign examples, to illustrate 

 the English forms found within the genus Fitmea. He read 

 some notes relating to the genus, and to characters, chiefly 

 drawn from structure, by which the different species may be dis- 

 tinguished.— Mr. Malcolm Burr called attention to Dr. Sharp's 

 paper on the modification and attitude of Idoliim diaboltcton. 



NO. 1573. ^'OL. 61] 



recently published in the Proceedings of the Cambridge Philo- 

 sophical Society (vol. x. pal-t iii.). He exhibited the plate, 

 drawn after nature by Mr. Muir, which illustrates the paper, 

 pointing out that no drawing of this kind showing a Mantid in 

 its natural colours simulating the petals of a flower, had hitherto 

 been published. He also exhibited species of Mantodea of 

 various genera, to show the diff'erent modifications by means of 

 which insects of this group are maide to resemble leaves and 

 flowers. — Mr. Kenneth J. Morton communicated a paper en- 

 titled "Descriptions of new species of Oriental Rhyacophilae." 



Dublin. 

 Royal Dublin Society, November 22. — Prof, E. J. 

 McWeeney in the chair.— Prof. T. Johnson read a paper on 

 the yellow blight of the potato-plant, an examination of which 

 he had undertaken at the request of the Congested Districts 

 Board of Ireland. The disease is especially prevalent in the 

 west, but is found throughout Ireland. The two fungi held 

 mainly responsible for the disease, of which an illustrated 

 account was given, are considered to be Sclerotinia sclerotiorum 

 (Lib.), Massee, and Khizoctonia Solani, Kiihn, the "small- 

 pox " fungus of the potato-tuber. At the Winter Show of the 

 Royal Dublin Society, of several hundred dishes of potatoes 

 there was scarcely a dish with tubers free from the sclerotia and 

 mycelium of Khizoctonia, hitherto not recorded in Ireland. — 

 Mr. G. H. Carpenter read a paper on some Collembola from 

 Franz-Josef Land, collected by Mr. W. S. Bruce, of the Jackson- 

 Harmsworth Expedition in 1896 and 1897. Seven species are 

 represented in the collection, one of which — an Isotoma — is new 

 to science. Mr. Carpenter also presented a paper on Pantopoda 

 from the Arctic Seas, dredged by Mr. Bruce in 1897 and 1898. 

 —Dr. F. T. Trouton,F.R.S., exhibited Caldwell's modification 

 of the electrolytic interrupter, and drew attention to his explan- 

 ation of the curious transference flow which occurs from one side 

 to the other through the narrow opening or hole in the dividing 

 partition. The direction of the flow being independent of the 

 direction of the current points to a heating effect. When the 

 explosion in the hole occurs through the sudden evolution of 

 vapour liquid is ejected to both sides : but should the position 

 of the explosion in the hole move, through any cause, to one 

 side, more liquid will be thrown to the other. The bubbles of 

 vapour must tend to form on the side of lowest pressure, thus 

 accounting for the phenomenon. In the apparatus shown, the 

 number of breaks per second was about 750, the volume of the 

 hole about '001 1 c.c. ; thus the limit to the rate of flow is about 

 '4 c.c. The maximum observed was about '3. 



Royal Irish Academy, December 11.— Dr. Benjamin 

 Williamson, F.R.S. , in the chair. — Dr. Henry H. Dixon read a 

 paper on the first mitosis of the spore-mother cells of lilium. In 

 this paper observations and arguments are adduced in favour of 

 regarding the double twisted condition of the nuclear thread in this 

 mitosis as arising from the folding and twisting together of parts 

 of the dolichonematous thread. The double thread parting 

 transversely forms the chromosomes, which are thus composed 

 of two twisted portions, each a primary chromosome. In the 

 equatorial plate each primary chromosome divides longitudinally. 

 A pair of the longitudinal halves forms the V-shaped daughter 

 chromosome. It is also shown that the unravelling of the halves 

 of the twisted primary chromosomes naturally explains the 

 constant V-form of the daughter chromosomes. From this it 

 will be seen that the mitosis is not a "reducing" division in 

 Weismann's sense. The manner of the formation of the chromo- 

 somes brings into proximity in the dispirem stage parts of the 

 nuclear thread which were, in the spirem stage, distant from one 

 another. — Prof. C. J. Joly read a paper on some applications of 

 Hamilton's operator v in the calculus of variations. In the case 

 of positional variations, the conditions for a stationary value of the 



'miGgra\Jfdp,fdp being a linear and distributive function of the 



vector element dp of a curve, may be expressed by the relation 

 /Sp = o at the limit.s, s.nAfvvvdplp = o at each point of the curve. 

 In the second equation, V operates on / alone. For surface 



Fdw where dv is a directed element of area, the 



tgtz\s,,ffl 



conditions are Fv = o over the surface, and F\ = o oyer the 

 boundary, \ being normal to a fixed surface on which the 

 boundary lies. Examples were given for the use of these 

 formulis. 



