174 



NATURE 



[Dec. 28, 1 87 1 



distance of the centres of the Sun and of Venus during tlie 

 transits of that pianet. — M. P. J. Van Beneden deicfibes a new 

 Sirenian from the Rupelian stage. The remains of this animal 

 were olitaincd at Elsloo, near Maeslricht, and consist of a por- 

 tion of the cranium, one dorsal vertebra, and a series of seven 

 caudal vertebr;T^. Tiiese are described and figured by M. Van 

 Beneden under the name of Crassit/wriiiin rohustuin ; he regards 

 it as more nearly allied to the SteUet-ir than to the Manatees and 

 Dugongs. M. Van Beneden also notices the occurrence at Basel 

 near Rupelmonde of a nearly complete skeleton of a Sirenian 

 in brick-clay, and remarks upon the constant association of re- 

 mains of Squalodon with those of Sirenians wherever the latter 

 have been found in Europe. He also notice; some points in the 

 osteology of living Sirenia. — M. E. Van Beneden gives us a 

 note on the preservation of the lower animals, in which he re- 

 commends the employment of .solutions of osmic acid and picric 

 acid for the preservation of the more delicate forms of animal 

 life, such as the Medusre, Ctenophora, &c. According to him 

 these processes are most successful. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, December 21. — "Contributions to the His- 

 tory of Orcin.— No H. Chlorine and Bromine- substitution Com- 

 pounds of the Orcins." By John Stenhouse, F.R.S. 



" Note on Fucusol." By John Stenhouse, F.R.S. 



Mathematical Society, December 14. — Dr. Spottiswoode, 

 president, F.R.S., in the chair. Mr. K. Freeman, of St. John's 

 College, Cambridge, was elected an ordinary member, and the 

 following gentlemen foreign members of the Society .- — Dr. 

 Clebsch, M. Hermite, Prof. Cremona, Dr. Hesse, and Prof. 

 Betti. Dr. Sylvester explained the methods he had employed in 

 his paper, "On the theorem that an arithmetical progression 

 which contains more than one contains an infinite number of 

 prime numbers." The communication was limited to the case of 

 arithmetical progressions proceeding according to the common 

 difference, 4 or 6. The method employed appears to differ fun- 

 damentally from Dirichlet's method (Berlin 'I'ninsactions, 1837). 

 [In the account of Dr. Sylvester's previous communication to the 

 Mathematical Society, given in Nature, Nov. 23, p. 75, at 

 line 18 from the commencement of the paragraph, for ininition 

 read induction, and at line 20 from the foot of the page, for the 

 words //it' magnitude read the order of tlie magnilitde.'\ Profs. 

 Cayley and H. J. S. Smith took part in a discussion on the sub- 

 ject. — Prof. Clifford next spoke with reference to a paper, he is 

 preparing for the society. — Prof. Cayley then drew attention to 

 the question of the determination of the surfaces capable of 

 division into infinitesimal squares by means of their curves of 

 curvature. It was shown by M. Bertrand that in a triple system of 

 orthotomic isothermal surfaces each surface possesses the property 

 in question, of divisibility into squares by means of its curves of 

 curvature. But in such a triple system each surface of the system 

 is necessarily a quadric. There is nothing to show that the property 

 is confined to quadric surfaces, and the question of the determina- 

 tion of the surfaces possessing the property appears to be one of 

 considerable difficulty, and which has not hitherto been examined. 

 — Mr. S. Roberts exhibited a thread model of a homographic trans- 

 formation of the developable surface which circumscribes a system 

 of compound quadrics. The surface is generated by planes touching 

 an ellipse at a constant inclination, and its equation is obtained 

 by writing/- z- for ?- in (p (x-, y^, r') = o representing the plane 

 parallel of an ellipse. 



Anthropological Institute, December 18. — Dr. Charnock, 

 president, in the chair. Lord Dunraven, Dr. John Best, 

 and Mr. J. Kerape were elected members. A paper was 

 read by Mr. Joseph Kaines on the " Anthropology of Augusta 

 Comte." The sources of the paper were to be found in 

 chapters on "Biology" and "Fetishism" of M. Comte's 

 Philosophie Positive and in the Politique Positive. The paper itself 

 aimed to show that the differences between man and the rest of 

 the animal kingdom were not so great as they were usually re- 

 presented, nor in fact were they so numerous in their resem- 

 blances. Treating man as the head of the zoological series, it 

 argued that his dominion over animals was from primitive times 

 (and is now) a moral dominion rather than intellectual, and it 

 concluded, that in so far as external nature was used by man for 



moral ends, it was riglitly used, and that the intellect found its 

 true work in directing his affec ive nature to moral purposes and 

 relationships. 



Linnean Society, December 21. — Mr. G. Bentham, F.R.S., 

 ]5resident, in the chair. " On the Anatomy of the American 

 King-Crab [Limulus polypheinus, Latr.)," by Prof. Owen, F.R.S. 

 Tlic author, referring to anatomies of existing species of animals 

 elucidating the type of structure of large extinct groups — as that 

 of Apteryx in reference to the DinoniitliidiC ; of Protopterus in 

 relation to the notochordal, protocercal Cycloganoids of paljeozoic 

 beds ; of Nautilus as the repressntative of the constructors of 

 extinct chambered and siphonated shells ; of Orbieula, Discina, 

 and Terelratida'}t\ like relation to extinct Brac/nopcda — stated that, 

 in reference to the Trilobite Crustacea, he had once doubted 

 whether Serolis or Linudus would reflect most light on the 

 intern.al structure of those ancient forms of the class. But, in 

 the 14th lecture of the Hunterian Course of 1S43, published in 

 April of that year, appreciating the importance of the character 

 by which the Xiphosures and Trilobites agreed in differing from 

 Malacostrjca, viz., in the numerical formula of segments, he 

 decided to take Limulus in hand. Isopodal tendencies in 

 Trilobites indicated, however, their more generalised character, 

 and continued palxontologicol research lect to the postponement 

 of the original purpose, until the subsequent discoveries of a 

 palaiozoic group of Crustacea, due mainly to the labours of 

 Salter, Huxley, and Woodward, decided the author no longer 

 to delay the present communication, in view of its more special 

 bearings upon the Merostotnata of the last-named carcinologist. 

 Of the external characters of Limulus but little was left to de- 

 scribe. The author accepted the evidence of the homologies of 

 the three divisions of the body adduced bv Dana, Spence Bate, 

 and Woodward as outweighing that which influences V. der 

 Hoeven. The " cephalothorax " of the latter author was the 

 " cephalon," the second division was, not the "abdomen," but 

 the "thorax," of the later carcinologists. The determination 

 by the latter of the articulated appendages of the foremost divi- 

 sion of the body of Limulus was also adopted. But as that 

 division includes not only the brain, organs of sense, mouth, and 

 manducatory instruments, but also the stomach, liver, major 

 part of the lieart, and genital organs, together with a long tract 

 of the ventral ganglionic neural chords or centres, the author 

 proposed to speak of it as the " cephaletron," the succeeding 

 division as the " thoracetron," for the spine-shaped part he 

 adopted Spence Bate's term of " pleon." In the description of 

 the cephaletron, its modifications enabling it to act effectively as a 

 burrowing digger or spade were dwelt upon, and the modifica- 

 tions of the hind border which articulates with the thoracetron 

 were pointed out, showing that whilst by coalescence it was part 

 of the foremost division in all its formal characters, more espe- 

 cially its upper pair of entapophysial pits and under pair of 

 coalesced lamelliform appendages, it belonged to the series of 

 lamelligerous segments constituting the thoracelron. The author 

 then proceeded to give a detailed account of the muscular system 

 of Limulus, and concluded this third section of the paper, by 

 condensing notes made by Mr. Lloyd, of the Crystal Palace 

 Aquarium, on the movements of living Liinuli in captivity, and 

 those made by Mr. Lockyer in New Jersey on the Lixmilus poly- 

 pliemus in its native seas. The reading of this memoir will be 

 continued at a subsequent meeting of the Linnean Society. 



Manchester 

 Literary and Philosophical Society, November 28. — 

 Dr. J. P. Joule, F.R.S., vice-president, in the chair. "Encke's 

 Comet and the Supposed Resisting Menium," by Professor 

 W. Stanley Jevons. The observed regular diminution of 

 period of Encke's comet is still, I believe, an unexplained pheno- 

 menon for which it is necessary to invent a special hypothesis, a 

 Deus ex mae/iina, in the shape of an imaginary resisting medium, 

 I cannot be sure that the suggestion I am about to make has not 

 already been made, but I have never happened to meet with it ; 

 and therefore I venture to point out how it seems likely that the 

 retardation of the comet may be reconciled with known physical 

 laws. It is asserted by ]\Ir. R. A. Proctor, Prof. Osborne Rey- 

 nolds, and possibly others, that comets owe many of their peculiar 

 phenomena to electric action. I need not enter upon any con- 

 jectures as to the exact nature of the electric disturbance, and I 

 do not adopt any one thcoiy of cometary constitution more than 

 another. I merely point out that if the approach of a comet to 

 the sun causes the development of electricity arising from the 

 comet's motion, a certain resistance is at once accoimted for. 



