June 25, 1896] 



NA rURE 



191 



as highly probable that it was a remarkable form of l.etnaitia 

 palUiis, but that more material was required before a final 

 opinion could be formed. The remarkable transverse (elbowed) 

 line of dots crossing the forewings was exactly parallel with that 

 of l.ciicania slramiiiea and L. imptira ab. pitnctalinca, and for 

 an aberration of this character to occur in /,. palkiis was as pro- 

 bable as in /,. imptira, the typical form of which is but sparingly 

 dotted in the direction of the elbowed line. The hindwings 

 showed almost identically the same characters in the dark shading, 

 traces of dots in nervures, &c. , as the red aberrations of Z. paliens 

 exhibited by Mr. Mathew. He considered that until the matter 

 of its specific distinctness was finally settled, Mr. Barrett had 

 erred on the right side in giving it a distinctive name, even if the 

 name subsequently fell as an aberration of /,. pa/lens. — Mr. 

 Waterhouse exhibited several branches of oaks from the New 

 Forest entirely denuded of foliage, and stated that throughout 

 large tracts of the forest the oaks had been stripped of their 

 leaves in the same fashion by Lepidopterous larva;, especially 

 Clieinialobia briimata, Hybeinia dcfoliaria, and Tortrix 

 vin'daiia. Certain trees, however, though situated among the 

 denuded trees, had quite escaped. Dr. Sharp suggested that 

 they belonged to a different species ; but Mr. Waterhouse said 

 that he had carefully e.xainined them, and that this was not the 

 case. Mr. McLachlan said that the immunity of the trees 

 referred to was probably due to irregularity in coming into leaf 

 — Mr. Tutt exhibited living pupre of Eiwdia hyperanthiis and 

 Epiiiepheic iaiiira, and pointed out how different the pupa: of 

 these two species were in general appearance, structure, and 

 cremastral attachment from each other. He pointed out that 

 these two species had for a long time been erroneously placed in 

 the same genus, but that, in all stages, they were widely 

 separated, and that not only should they be placed in different 

 genera, but that they appeared to belong to different 

 tribes — Eiiodia /lypeniiit/ius being in the Cu-nonyinphidi and 

 EpiiKphele ianira in the Epinephclidi (mdc Entom. Kecord, vii. 

 p. 301). — Mr. Blandford exhibited and described series of 

 tropical American butterflies from the Godnian-Salvin collection, 

 arranged to show the existence and geographical distribution of 

 homicochromatic groups. — Dr. Chapman communicated a paper 

 on the phylogeny and evolution of the Lepidoptera from a pupal 

 and oval standpoint. 



Geological Society, June ic— Dr. Henry Hicks, F.R.S., 

 President, in the chair. — On foliated granites and the relations to 

 the cr)-stalline schists in Eastern Sutherland, by J. Home and E. 

 Cireenly. The crystalline schists of Eastern Sutherland are 

 traversed by great numbers of granitic intrusions, chiefly in the 

 form of lenticular sills. These generally lie parallel to the 

 foliation-planes of the schists, but transgressive junctions are 

 also frequent. Thin seams of granite also occur in such abun- 

 dance as to constitute with the schists a banded gneissic series ; 

 but these seams can often be seen to transgress the schistose 

 folia, and even often to proceed from large masses of granite. 

 The granites contain numerous inclusions of the schists which 

 they traverse, such inclusions retaining, usually, the dip and 

 strike of the surrounding rocks. There are no chilled edges ; 

 and, moreover, the component crystals of schist and granite 

 mutually interlock along the line of junction. The authors 

 gave an account of the foliation of the granite. In some rare 

 cases a foliation parallel to that of the schists traverses granite- 

 veins. It is genetally, however, parallel at once to the sides of 

 the sill and to the foliation of the schists ; and many of the 

 structures are the remains of biotite folia belonging to schists 

 whose quartzo-felspathic elements have been incorporated with 

 those of the granite. But many sills or veins, traversing the 

 schists at various angles, are foliated parallel to the line of 

 junction, and so discordantly to the structures in the schists ; 

 and foliated granites may even be observed to cut each other's 

 foliation. These can hardly be anything but original igneous 

 structures ; but, if coexistent with the last-named, would be 

 indistinguishable from it. The country-rocks are various types 

 of biotite-schist or gneiss, with quartz-schists at Kildonan, 

 and a scapolite-limestone at Armadale. They are almost 

 all holocrystalline, but it is certain that sedimentary rocks 

 enter into the complex. The whole series is power- 

 fully folded. The granites increase in size and numbers 

 north-westward from Kildonan ; the intimate intrusive 

 relations alxjve described becoming more highly developed in 

 the same direction. The schists, at the same time, become 

 more and more highly crystalline, sillimanite also appearing in 

 them. About Kinbrace they are coarse sillimanite-biotite- 



NO. I 39 1, VOL. 54] 



gneisses, with large striated felspars. Igneous contact was not 

 held to be the sole origin of metamorphism, though the cause 

 which brought about the introduction of the granites had evi- 

 ilently also produced these high types of crystallisation. The 

 evidence of powerful movement which the schists everywhere 

 present suggested that such movement was the initial cause of 

 the whole series of phenomena. Movement recurred through- 

 out, though all cataclastic structures (if such existed) had been 

 wholly effaced by crj-stallisation ; introduction of granite being 

 the final stage in the production of the complex, and a high 

 temperature (as shown by the alisence of chilled edges) being 

 maintained to the very end. With regard to the granites, the 

 authors found it difficult to believe that they are wholly foreiga 

 matter, but remark that it is necessary to observe the utmost 

 caution with reference to it. — The geology of the eastern 

 corner of Anglesey, by E. Greenly. — Seismic phenomena in 

 the British Empire, by M. F. de Montessus de Ballore, 

 Captain of Fortress Artillery at Belle-Ile-en-Mer. The author 

 gave a brief outline of a plan that he has elaborated for study- 

 ing seismology. He has separated his work into four parts : 

 (i) The formation of an earthquake catalogue. (2) Refutation 

 of the empirical laws previously ennuciated. (3) Description of 

 the globe from a seismological point of view. (4) Investigation 

 of the characters which differentiate stable from unstable regions. 

 He gave a method by which the relative seisiiiicily (or instability 

 as regards earthquakes) of regions may be obtained and 

 registered, and indicated some of the results which he had 

 derived from his study, including the intimate relationship 

 between instability and surface-relief, and the independence of 

 seismic and volcanic phenomena. The main part of the paper 

 was a section of the third division of the author's work, and 

 dealt in detail with the earthquakes of the British Empire. In 

 this part of the paper, the recorded earthquakes of the British 

 Isles, India, Australia and New Zealand, British Africa, Canada, 

 and various scattered possessions were described. 



Edinburgh. 

 Royal Society, June 15.— Prof Geikie in the chair.— Mr. 

 A. T. Masterman read a note on the structure of Actinotrocha 

 considered in relation to the chordate affinities of Phoronis. In 

 this paper, the author demonstrated the presence of a paired 

 notochord in Actinotrocha which atrophies before the adult stage 

 is reached, probably at the metamorphosis. He also showed 

 the presence of five body-cavities in the larval stage. For these 

 and other reasons he claimed for Phoronis a place among the 

 Chordata, and proposed to place it in a separate division of this 

 group — the Diplochordata. The relationship of Phoronis to 

 Balanog/ossiis may be compared to that of the Tunicata to 

 Ainphioxus. — Prof Tait read a paper on Clerk-Maxwell's law 

 of distribution of velocities in a group of equal colliding spheres. 

 He adverted to the extraordinary denunciation by M. Bertrand 

 of Clerk-Maxwell's proof of the fundamental law of the kinetic 

 theory of gases. He showed that Maxwell's proof involved none 

 of the absurdities alleged by M. Bertrand, and that the gist of 

 the matter was this : — There is a iinicjtie solution of the problem : 

 Maxwell's is a solution, because it is not interfered with by 

 collisions ; therefore it is the solution. — Prof Chrystal gave a 

 summary of a paper on the / discriminant of a differential 

 equation of the first order, in which he applied Newton's method 

 of approximation (first employed in the theory of differential 

 equations by Briotand Bouquet) to prove some leading theorems 

 regarding the / discriminant locus, most of which had previously 

 been established by Darboux by other methods. He showed that 

 the p discriminant locus (A), <p(.\\ y, p) = o, <pf{.x, y, p) = o is, 

 in general, a cusp-locus for the family of integral curves. He 

 also established that the locus, if)(.r, y, p) = o, <t>.v{-ir, y, p) + 

 ptpyi-x, y, p) = o, is in general an inflexion-locus (B), and that 

 <(>(■>■, y, p) = o, p<pje{-r, y, p) - (p,{.x, y, p) = o is a locus of 

 inflexions on the orthogonal trajectories of the integral family 

 (C). --^ny point of intersection of A and B, is, in general, a point 

 at which two integral curves touch each other, and also touch A. 

 The necessary and, in general, sufficient condition for an 

 envelope singular solution is that A and B have a branch in 

 common. The necessary and, in general, sufficient condition that 

 two integral curves touch, and do not touch A, is that A, B, C have 

 a point in common. The necessary and, in general, sufficient con- 

 dition for a tac-locus is that A, B, C have a branch in common ; 

 the characteristic of this branch appearsasasquaredfactor in the 

 / discriminant. Prof. Chrystal then proceeded to refute a pro- 

 position of Cayley's, "that a difterential equation of the first 



