476 



NATURE 



[March 17, 1898 



to start from the secoi\dary deposit which unites the rays at the 

 centre. Much skill and care have been bestowed on the beautiful 

 drawings illustrating these researches, and they are admirably 

 reproduced in an excellent series of plates. — Prof. MacBride, in 

 a paper on the early development of Amphioxus, shows the 

 similarity between the ccElomic chambers of Amphioxus and 

 Balanoglossus, and homologises the metapleural lymph canals of 

 the former with portions of the collar pouches of the latter ; in 

 consequence of this he revives Bateson's comparison of the 

 atrial folds of Amphioxus with the posterior collar folds of 

 Balanoglossus. — Mr. Shipley gives an account of a new Tape- 

 worm from a bird in the Sandwich Islands. — Dr. Willey gives 

 the diagnosis of a new genus of Enteropneusta. — Prof. Haswell 

 describes a Turbellarian from deep wells in New Zealand. — Prof. 

 Ray Lankester, in a note on the development of the atrial 

 chamber of Amphioxus, corrects Prof. MacBride's statements 

 with regard to the well-known researches by himself and Dr. 

 Willey on the development of the atrial chamber. 



Bulletin of the American Mathematical Society, February. 

 — The number opens with an account of the fourth annual 

 meeting of the Society on December 29, 1897. After the 

 election of the new Council — Prof. S. Newcomb being re- 

 elected President — eleven papers were presented ; of some of 

 these abstracts are given, and the journals in which they have 

 appeared, or will appear, are named. — Prof Woodward's paper 

 on the differential equations defining the Laplacian distribution 

 of density, pressure, and acceleration of gravity in the earth 

 presents an improved mathematical method for the treatment of 

 the problem, previous methods being deemed by the author to 

 be lacking in elegance and compactness. — The following are to 

 appear in the American lournal 0/ Mathematics — viz. on 

 some points of the theory of functions, by Prof Chessin ; and 

 point-transformation in elliptic coordinates of circles having 

 double contact with a conic, by Dr. Lovett. A second paper by 

 Dr. Lovett, entitled " Certain invariants of a plane quadrangle 

 by projective transformation," will be published in the Annals of 

 Mathematics. It is a contribution to the theory of a system of 

 4-coplanar points, and shows among other things how tfie 

 group theory may be made to yield the details of elementary 

 geometry. — Prof. Newcomb's presidential address, given in 

 extenso, treats of the philosophy of hyperspace. "There is a 

 region of mathematical thought," he remarks, " which might be 

 called the fairyland of geometry. The geometer here disports 

 himself in a way which, to the non-mathematical thinker, sug- 

 gests the wild flight of an unbridled imagination rather than 

 the sober sequence of mathematical demonstration." He defines 

 his hyperspace as being, in general, space in which the axioms 

 of the Euclidean geometry are not true and complete. Curved 

 space and space of four or more dimensions are completely dis- 

 tinct in their characteristics, and must therefore be treated 

 separately. Prof. Newcomb's views have already been stated 

 in our columns, and the present address is an interesting sequel 

 to them up to date. — Another of the papers, viz. orthogonal 

 group in a Galois field, by Dr. L. E. Dickson, is also given 

 here. The term orthogonal, in the present connection, is 

 defined, and a remark of Jordan's shown to be not exact 

 {Trait J des Substitutions, p. 169,//. 18-21). — We can merely 

 mention that the second meeting of the Chicago Section was 

 held on December 30 and 31, 1897, at which twenty-one papers 

 were read. Brief abstracts are given. From the Notes we 

 learn that in the year 1897 the membership of the Society 

 increased from 280 to 301, and the total number of papers read 

 was 88! 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, January 27.—" On the Zoological Evidence 

 for the Connection of Lake Tanganyika with the Sea." By 

 T. E. S. Moore, A.R.C.S. 



The results of the morphological examination of the animals 

 obtained during the author's recent expedition to Lake Tan- 

 ganyika have made it evident that the fauna of this lake must 

 be regarded as a double series, each half of which is entirely 

 distinct in origin and nature from the other. The remarkable 

 Molluscan shells which were brought home by Burton and 

 Speke, form but a small part of the Molluscan section of the 

 more abnormal of these fresh-water stocks. Besides Molluscs, 



the lake was found to contain fishes, Crustacea, Ccelenterata, 

 and Protozoa, all of which, like Speke's shells, present the most 

 curious marine affinities, and for distinctive purposes the in- 

 dividual members of this unique assemblage of quasi-marine 

 fresh-water organisms are described as members of the Halo- 

 limnic group. 



The distribution of the aquatic faunas occurring in Lakes 

 Shirwa, Nyanza, Kela and Tanganyika, all of which were 

 visited and dredged during the expedition, shows (together with 

 what is already known respecting the Victoria Nyanza and the 

 more northern lakes) that the Halolimnic animals are exclu- 

 sively restricted to Tanganyika. It is thus rendered incpn- 

 ceivable that the Halolimnic forms can have arisen through the 

 effect of ordinary conditions operating upon the population 

 which the lake originally possessed. For the same reasons, it 

 becomes equally clear that the Halolimnic animals cannot be 

 regarded as the survivors of an old fresh- water stock. Since, if 

 we accept either of these suppositions, we are bound by the 

 facts of distribution to believe, also, that the Halolimnic animals 

 have been destroyed in every African lake but one ; a suppos- 

 ition which may be ingenious, but which, when the number of 

 lakes existing in the African interior is fully realised, becomes 

 grotesque. 



Apart from the physical difficulties which the present effluent 

 of Tanganyika presents to the ingress of organisms from the 

 sea, it is impossible to regard the Halolimnic forms as having 

 recently transmigrated thither from the ocean, since none of 

 these animals are exactly similar to any marine organisms at 

 present known. They must, therefore, have been in Tangan- 

 yika long enough to modify into their present condition from 

 the living oceanic species which we know, or they retain the 

 characters of a sea-fauna that has elsewhere become extinct. 



The delicate nature of the lake Medusre, and the fact that 

 most of the Halolimnic Molluscs are exclusively deep-water 

 forms, renders it impossible that these organisms can have made 

 their way into Tanganyika at any time under the physical 

 conditions which now exist. 



The facts of distribution and the general characters of these 

 forms, as well as the geographical conditions of the lake in 

 which they are now found, lead then to the conclusion that the 

 Tanganyika region of Central Africa must have approximated 

 to a deep arm of the sea in ancient times. 



This view is finally confirmed by the details of the anatomy 

 of the Halolimnic animals themselves. For some of the in- 

 dividual Molluscs of this group combine the characters of several 

 of the most modern marine genera. The Halolimnic fauna of 

 Tanganyika, therefore, cannot represent an extinct fresh-water 

 stock, since the characteristic fresh-water organisms of the 

 present day (which would in such a case have to be regarded 

 as their linear descendants) possess the anatomy of vastly older 

 types. 



To the Halolimnic animals there thus attaches the unique 

 interest that they themselves constitute the few surviving in- 

 dications of an old sea which once extended far into the African 

 interior, and which, judging from the characters of the animals 

 it left behind, must have retained its connection with the ocean 

 at least as late as Tertiary times. 



These conclusions, it will be observed, are directly in op- 

 position to the views which were originated by Murchison, 

 and which depict the African interior as never having been 

 below the sea at least since the New Red Sandstone age. 



February 17. — "On the Magnetic Deformation of Nickel." 

 By E. Taylor Jones, D.Sc. 



The experiments were made with a view to further testing a 

 result arrived at on a former occasion by the author, viz. that 

 the magnetic contraction of a long nickel wire was approximately 

 proportional, when allowance was made for the effects of Kirch- 

 hoffs system of stresses, to the fourth power of the magnetisa- 

 tion. 



In order to vary, if possible, the conditions of the experiments 

 some preliminary measurements were made to find out whether 

 temperature had any marked influence on the magnetic contrac- 

 tion. The temperature of the specimen was raised by allowing 

 warm water to flow through the water-jacket of the magnetising 

 coil. It was found that at low field-strengths (up to about 90 

 C.G.S. ) the magnetic contraction was greater at 56° C. than at 

 19° C. ; at higher fields the contraction was greater at the lower 

 temperature, the difference Being about 6 per cent, at the field 

 330 COS. 



Repeated measurements showed that the contraction at any 



NO. 1 48 I, VOL. 57] 



