May lo, 1877] 



NA TURE 



be possibly the eggs of the Cuckoo. Mr. Howard Saunders 

 also exhibited two skins of Dupont's Lark {Certhilauda dufonti) 

 from the same locality. — Prof. St. George Mivart read a paper 

 on the axial skeleton of the Pelicanida;, selecting Pelicjiuis as 

 his type and standard of comparison. Prof. Mivart first com- 

 pared it, as regards its axial skeleton, :with Slritth'O, and the 

 other Stiuthienidu-, and then compared the other Steganopodes 

 with it and with one another. — A communication was read from 

 Dr. M. Watson, Professor of Anatomy, Owens College, Man- 

 chester, on the anatomy of Hyirna crocuta, in which he described 

 the very peculiar conformation of the female generative organs 

 of that animal. — Mr. A. G. Butler read a paper wherein he gave 

 the description of two small collections of Heterocerous Lepi- 

 doptera from New Zealand, recently brought to England by Dr. 

 Hector and Mr. J. D. Enys. — -A communication was read from 

 Dr. O. Finsch giving an account of a small collection of birds 

 from the Marquesas Islands. Amongst these were three exam- 

 ples of a new species of Kingfisher, proposed to be called Hal- 

 fvoii god,(lroyi. — A communication from Mr. Frederick Smith 

 contained descriptions of four new species of Ichneumonid;i; in 

 the collection of the British Museum. Amongst these was a new 

 Bracon, remarkable for having its ovi-positor more than nine 

 times the length of its body. This was proposed to be called 

 Bracon poietratror, and had been received from Yokohama, 

 Japan. — Prof. A. H. Garrod read some notes on the anatomy 

 and systematic position of the genera Thincorns and Atta^is, 

 which he considered should be referred to the Limicolae in the 

 neighbourhood of Glareola and Cursorius. 



Geological Society, April 25. — Prof. P. Martin Duncan, 

 F.R.S., president, in the chair. — Messrs. S. Bewsher, H. G. 

 Bolam, Charles Thomas, and John M'Kenzie Knight were 

 elected fellows of the Society. — On the upper limit of the essen- 

 tially marine beds of the Carboniferous system, and the necessity 

 for the establishment of a "Middle Carboniferous Group," by 

 Priif. 1;. Hull, F.R.S. The author, in this paper, divided the 

 whole of the Carboniferous rocks into successive stages from A 

 to G inclusive, taking the Carboniferous beds of Lancashire as a 

 type, and showed that these stages could be identified over tlie 

 whole of the British Isles. It was only recently that their deter 

 mination had been made in Ireland, so that until now the mote- 

 rials had not existed for a complete correlation of the series in- 

 the British Islands. The following is an abbreviated state ment 

 of the representative stages in descending order : 



Essentially Freihwater 



Estuarme, vith one or two Marine 

 Bands. 



Stage G. — Upper Coal-measures of Lancashire (2,000 feet) 

 and other English coal-fields. Red Sandstones, &c., of Bothwell 

 and Ayr, in Scotland. (Absent in Ireland.) 



Stage F. — Middle Coal-measures of Lancashire, &c., with 

 principal coal-seams (3,000 feet). "Flat coal-series" of Scot- 

 land. Present in Ireland (Tyrone, Kilkenny). 



Essentially Marine. 



Stage E. — " Gannister Beds'" (Phillips), with marine shells 

 and thin coals (2,000 feet), in Lancashire. " Pennystone series" 

 of Coalbrook Dale, South Wales, &c. "Slaty black-band" 

 series of Scotland. (Present in Ireland, Kilkenny, Dungannon, 

 Lough -Mien coal-fields.) Also in Belgium, Rhenish Provinces, 

 and Silesia, with numerous marine shells. 



Stack Y).— Millstone Grit Series of England and \Vale=. 

 3,500 feet in Lancashire; " Moorstone Rock" of Scotland; 

 "Flagstone-series" of Carlow and Kilkenny ; MiUstone-gri'. uf 

 Femianagh and Leitrim, with coals and marine shells. 



Stage C. — Yoredale Beds. 3,000 feet in Lancashire ; Upper 

 Limestones and " Lower Coal and Ironstone series" of Scot- 

 land ; Shale series of Kilkenny and Carlow ; Ironstone shales of 

 Lough Allen, with marine shells. 



Stage B. — Carboniferous Limestone. Mountain Limestone 

 of Derbyshire; "Scaur Limestone" in Yorkshire; "Lower 

 Limestone " (Roman camp) of Scotland ; Carboniferous Lime- 

 stone of Ireland. 



Stage A. — Lo-uier Limestone Shale of England. Calciferous 

 Sandstone series ("Tuedian," Tate) of north of England and 

 Scotland ; Lower Carboniferous Sandstone, north ot Ireland ; 

 Lower Carboniferous slate, with Coomhola grits, with marine 

 shells, south of Ireland. (In Scotland, estuarine or lacustrine.) 



Palifontolopcal Results. — On making a census of the Molluscan 

 and other fossils from the various stages ^above that of the Car- 

 boniferous limestone (stage B) as determined by the palieontolo- 



gist of the Geological Survey, some interesting results were 

 obtained, showing the prevalence of marine conditions up into 

 stage E, and a general change in the character of the fauna in 

 the succeeding stages. Including only the area of the British 

 Islands, it was found that no fewer than thirty-seven genera, with 

 seventy-four or seventy-five species, of decidedly marine forms, 

 occur in the Gannister beds (stage E), of which all the genera 

 and about forty species were known in the stage of the Carboni- 

 ferous Liuiestone. The series includes PhUlipsia^ which has been 

 found by Dr. F. Romer, in the representatives of stage E in 

 Silesia. On the other hand, of the whole number of species in 

 stage E (Gannister beds), only six are known in the overlying 

 stages F and G, these being characterised by the prevalence ot 

 bivalves of supposed lacustrine or estuarine habitats, variously 

 called Unio and Anthracosia. Of the few species of marine 

 genera known in stage F (Middle Coal-measures), about five or 

 six species are peculiar to itself, according to the determination 

 of the late Mr. Salter. Such a remarkable difference in the 

 fauna of the Upper and Middle Coal-measures, as compared 

 with that of the Gannister beds, constituted, in the author's 

 opinion, sufficient grounds for drawing a divisional line between 

 these two divisions of the Carboniferous series. Of the several 

 existing methods of classification adopted by different authors, 

 none of them appeared sufficiently to recognise the palceontolo- 

 gical distinctions and characteristics of the several formations. 

 The large number of genera and species which are now known 

 to range up from the Carboniferous Limestone into the Gannister 

 beds, and no higher, indicated the proper horizon for a divisional 

 line, in fact a palieontological break at the top of the Gannister 

 beds. On the other hand, the mineral and paloeontological 

 differences between the Carboniferous Limestone and the over- 

 lying Yoredale series were sufficient to justify their separation 

 into distinct divisions ; while the Yoredale, MilLtoue-grit, and 

 Gannister series are related by close mineral and palreontological 

 resemblances. With a view, therefore, of bringing the classifi- 

 cation of the Carboniferous series into harmony with the cha- 

 racter of the representative faunas, and the physical features of 

 the successive stages, the author suggests that stages C, D, and 

 E, composed of essentially marine beds, should be united into a 

 Middle Carboniferous group ; while stages F and G would 

 remain as at present, in the Upper Carboniferous, their fauna 

 being essentially of fresh water. In the discussion which fol- 

 lowed. Professors Ramsay, Boyd-Dawkins, Prestwich, and 

 Hughes seemed to doubt the feasibility of permanently main- 

 taining the lines of demarcation laid down in the paper. — On 

 coal-pebbles and their derivation, by H. K. Jordan, E.G. S. 



Physical Society, April 28. — Prof. G. C. Foster, president, 

 in the chair. — Mr. W. Ackroyd described some methods of 

 studying selective absorption in relation to the doctrine of aggre- 

 gation. After referring to the absorption of iodine vaj our and 

 iodine violet solutions he showed that an analogy exists between 

 these solutions and the aniline dyes, and a method was indicated 

 by which the approximate size of the particles affecting light 

 might be estimated. — Prof. H. McLeod exhibited .several forms 

 of apparatus which he has, in conjunction with Lieut. G. S. 

 Clarke, R.E., arranged for determining the speed of machinery, 

 &c., from observations made on the figures produced by com- 

 bining their motion with that of a vibrating body ; a description 

 of them has already been communicated to the Royal Society. 

 If a uniformly-moving point of light be rellected Irom a mirror 

 attached to a tuning-lork vibrating in a plane at right-jngles to 

 the motion of the point, the reflected image will appear as an 

 ordinary single wave, and a double figure of the form of a series 

 of figures of eight, caused by the overlapping of two waves, will 

 be funned if a series of points of light move uniformly with such 

 a velocity that a point passes over two intervals during an odd 

 number of vibrations of the fork. If equidistant perforations be 

 made in a circle on a disc which is [attached to a rotating axis 

 and the number of vibrations of the fork be known, the form of 

 figure reflected on to the screen will, theoretically, give the requi- 

 site data for determining the rate of rotation of the disc, and further, 

 a slight increase or decrease in this rate causes the figure slowly 

 to move in the same or opposite direction to the disc. If the 

 fork make 3,600 vibrations and the disc 100 revolutions per 

 minute, the circle must be divided into seventy-two equal intei- 

 vals, but for such a number as loi revolutions 71 '287 intervals 

 are needed. This fact would introduce some difficulty in pre- 

 paring an apparatus for measuring the velocity of rotation so as 

 to give the speed in whole numbers per minute, but it may be 

 obviated by ruling convergent white lines on dark paper and so 



