April IS, 1875] 



NA TURE 



479 



mean density mil always be vertical. Again, if n — 4, and 

 Pi + P4 = P2 ■*" P3 iPiP':l'3Pi teing the densities of the fluids), then 

 the diagonals of the square formed by the surfaces of the fluids 

 wUl be vertical and horizontal. This instrument, Prof. Wolsten- 

 holme suggests, might possibly be used as a level and plumb- 

 line ; perhaps, also, some interesting toys might be made by 

 other polygons. — A paper by Prof. J. Clerk-Maxwell, F.R.S., 

 on the application of Hamilton's characteristic function to optical 

 instruments symmetrical about an axis, and the value of the 

 function for a spherical surface, was taken as read. 



Geological Society, March 24.— Mr. John Evans, V.P.R S., 

 president, in the chair. — The President announced that the 

 late Sir Charles Lyell had bequeathed to the Society the 

 sum of 2,000/. for the purposes stated recently in our Notes, 

 p. 434. — Prof. Prestwich proposed and Mr. W. W. Smyth 

 seconded the following resolution : — " That this meeting, having 

 heard the announcement of the bequest made to the Geological 

 Society by the late Sir Charles Lyell, desire to record their (^eep 

 sense of the loss the Society has sustained by his death, and their 

 grateful appreciation of the liberal bequest for the advancement 

 of geological knowledge placed at their disposal by their late 

 distinguished Fellow." — The following communications were 

 read : — On the occurrence of phos^^hates in the Cambrian Rocks, 

 by Henry Hicks, F.G. S. In this paper the author showed 

 from experiments that the Cambrian strata in Wales contain a 

 far greater amount of phosphate and carbonate of lime than had 

 hitherto been supposed. The results published by Dr. Daubeny 

 some years ago, and which have since received the support of 

 some eminent geologists, were proved therefore to be entirely 

 fallacious when taken to represent the whole Cambrian series ; 

 for though some portions show only a trace of these ingredients, 

 there are other beds both interstratified with and underlying these 

 series, which contain them in unusually large proportions. The 

 author, therefore, objects to look upon Dr. Daubeny's experi- 

 ments as tending in any way to prove that the seas in which 

 these deposits had accumulated contained but little animal life, 

 and that we had here approached the borders of the lower limit 

 of organic existence. He contended that the presence of so 

 much phosphate of lime, and also of carbonate of lime, as was 

 now proved by analyses made by Mr. Hudleston, F.C.S., Mr. 

 Hughes, F.C.S., and himself, to be present in series of consider- 

 able thickness in the Longmynd group, Menevian group, and 

 Tremadoc group, proved that animal lite did exist in abundance 

 in these early seas, and that even here it must be considered that 

 we were far from the beginning of organic existence. The 

 amount of phosphate of lime in some of the beds was in the pro- 

 portion of nearly ten percent., and of carbonate of lime over 

 forty per cent. The proportion of phosphate of hme, therefore, 

 is greater than is found in most of what have been considered 

 the richest of recent formations. The amount of P2O5 was also 

 found to increase in proportion to the richness of the deposit in 

 organic remains. It was found that all animal and vegetable life 

 had contained it from the very earliest time ; but it was apparent 

 that the Crustacea were the chief producers of it in the early 

 seas ; and of the Crustacea, the trilobites more particularly. It 

 was always found where they were present, and the shell of some 

 of the larger trilobites, as now preserved, contained as much as 

 from forty to fifty per cent, of phosphate of lime. The analyses 

 made by Mr. Hudleston and the author, of recent Crustacea, 

 proved that they also contain V.fi^ in very considerable propor- 

 tions. In the second part of the paperthe author showed thatwhere 

 intrusive dykes had passed through or between the beds con- 

 taining the phosphate of lime, the beds for some distance on each 

 side of the dykes had undergone a considerable change. Scarcely 

 a trace of the P2O5 or of the hme was now to be found in them, 

 though it was evident that before the intrusions into them had 

 taken place, they, like the other portions of the beds, had evi- 

 dently contained both ingredients in considerable proportions. 

 It was well known that heat alone could not separate P2O5 from 

 lime ; theretore he found it difficult to account for this change 

 4n the character of the beds, unless it could be produced by 

 gases or watery vapour passing into them at the time the intru- 

 sions took place. He thought it even probable that the dykes, 

 which in some parts are found to contain a considerable amount 

 of lime and also of P0O5, might have derived these, or at least 

 some portions of these, from the beds through which they had 

 been lorced, and which must have been broken up and melted 

 as they passed through them. There are no contemporaneous 

 tuffs known in Wales of earlier date than the Llandeilo beds ; 

 and he thought these dykes belonged to that period, and that they 



were injected into the Lower Cambrian beds after from 8,000 to 

 lo,coo feet of deposit had been superimposed. In an agricul- 

 tural point of view the author considered that the presence of so 

 much phosphate of lime in some of the .series of beds mu^t be a 

 matter of great importance ; and on examining the districts 

 where these series occurred, he invariably found the land exceed- 

 ingly rich. Mr. Hudleston gave the results of the analyses made 

 by him at the request of Mr. Hicks. He found in a portion of 

 dark gray flaggy rock taken from close to a fossil i -62 in a 

 portion of black slaty rock containing trilobites, but in contact 

 with trap O'li, in'a portion of the shell of a trilobite I7'05, and in 

 the trap above-mentioned o'323 per cent, of phosphoric anhy- 

 dride. A lobster-shell dried at 100° C. gave 3'26, an entire 

 boiled lobster (undried) 076, and a boiled lobster without shell 

 0'332 per cent, of PnO,. If the analysis of an entire lobster be 

 correct, he estimated that a ton of boiled lobsters would contain 

 about 17 lbs. of phosphoric anhydride. In the analysis of a 

 shell of a trilobite there appears to be a great excess of phosphoric 

 acid, which Mr. Hudleston thought must be due to substitution. — 

 Note on the structure of the phosphatic nodules from the top of 

 the Bala Limestone in North Wales, by Mr. Hawkins Johnson, 

 F.G. S. In this paper the author described the appearances pre- 

 sented by thin sections made from some of the phosphatic 

 nodules and shales described by Mr. D. C. Davies, F.G.S., in his 

 recent paper. In both nodule and shale he finds structure which 

 he is inclined to identify with sponge-structure ; but the mass 

 also contains innumerable foreign bodies, chiefly fragments of the 

 shells of Mollusca and Crustacea, ^vith many irregularly ovate 

 bodies that remind him of Coscinopora, and some that may be 

 sponge-spicules. The author enumerated fourteen nodular for- 

 mations from various localities and of various composition, in 

 which he has detected organic structure, and to which he there- 

 fore assigns an organic origin ; and he protested against the 

 application of the term "concretionary" to such bodies. — On 

 the maxillary bone of a new Dinosaur, Priodontognathus Phil- 

 /ifsii coMdiined in the Woodwardian Museum of the University of 

 Cambridge, by Mr. Harry Govier Seeley, F.L.S., Professor of 

 Physical Geography in Bedford College, London. The bone 

 described in this paper was indicated by the author in his 

 " Index to the Aves, Omithosauria, and Reptilia in the Wood- 

 wardian Museum," under the name of Igiianodon Phillipsii. 

 Further examination and the detection of successional teeth 

 resembling those of Scelidosaurus, and those referred by Prof. 

 Huxley to Acaitthopholis, induced him to regard the species as 

 representing a new genus, most nearly related to Hylceosaiirus. 

 The specimen consists principally of the external and alveolar 

 portion of the left ma.xillary bone, which is 4J inches long, the 

 alveolar part being 4}, inches, and the remainder made up by a 

 posterior spur for connection with the malar. From the middle 

 of the upper margin springs an ascending nasal process, separat- 

 ing the orbit from the nasal aperture. The presence of the 

 posterior spur, or jugal process, seems to indicate an affinity to 

 the Iguanodontida;, notwithstanding the resemblance of the teeth 

 to those of Scetidosaurtts. The teeth, which are seen in their 

 sockets, have their crowns resembling those referred to Echino- 

 don, Scelidosaunis, and Acanthopholis, especially the last, differ- 

 ing chiefly by being relatively narrower, by having only 5-7 

 denticles on each side, by wanting the thickening at the base, 

 and by terminating in a sharp point. The author described in 

 detail the characters presented by the fossil, and indicated their 

 baring upon its systematic posirion. It was imbedded in a small 

 slab of yellow sandstone, wliich also contained a specimen of 

 Patcit varans, and is probably of Great Oolite age. — Description 

 of a new species of the genus Hemipata^us, Desor, from the 

 Tertiary Rocks of Victoria, Australia, with notes on some pre- 

 viously described species from South Australia, by Mr. R. Ethe- 

 ridge, jun.,'F.G.S. In this paper the author described anew 

 species of the genus Hemifaiagus, under the name of// M'oodsii, 

 and appended to this description some remarks on the characters 

 of Psammechimis Jt 'ivdsii, Laube, Micras/cr bmistclla, Laube, and 

 Monostychia aiistralis, Laube ; and also a synoptical Ust of the 

 Australian Tertiary Echinodermata hitherto described. 



Physical Society, April 10.— Prof. G. C. Foster, vice- 

 president, in the chair. — Prof. H. M'Leod communicated to the 

 Society some observations on the defects of the human eye as 

 regards achromatism. The eye has been considered to be achro- 

 matic because it practically is so ; but it is easy to offer abundant 

 eridence of the defects of the organ in this respect. For instance, 

 to short-sighted persons the moon appears to have a blue fringe. 

 In using the spectroscope, the red and blue ends of the spectrum 



