2o8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[August, 1905. 



two narrow bands, at greatest 47 mms. apart, and from this 

 measurement the curvature of the stream due to the field was 

 determined. From this the value of mass X by velocity -=- 

 charge of each particle can be calculated. The values ob- 

 tained are much more definite than previous ones. To com- 

 plete the calculation of the mass, it is necessary to deflect the 

 stream by an electrical field as well. This has not yet been 

 done, owing to the difficulty of quickly obtaining a sufficiently 

 high vacuum. 



If thin aluminium sheets are interposed the velocity of the 

 stream is reduced : and experiment shows that the photo- 

 graphic action ceases when the velocity is still 64 per cent, of 

 its initial value — i.e., when the velocity is about one-twentieth 

 that of light. The ionising and phosphorescent action also 

 cease at this velocity. This is a surprising result, for the 

 particle still possesses nearly 40 per cent, of its initial energy 

 at this stage. 



The similarity in respect to the three phenomena can be 

 most simply explained by supposing that photographic action 

 and phosphorence are essentially due to ionisation. 



It is most interesting to observe that the actual velocity of 

 emission is on the average only about 30 per cent, greater than 

 this critical velocity. The .\lpha stream would not have been 

 detected if its velocity had been much less than it is. Professor 

 Rutherford points out that disintegration may be taking place 

 in other substances and be practically undetectable, because 

 this lower limit of ionising velocity is not attained by the par- 

 ticles emitted. This remark may also apply to Radium B, 

 which is a so-called raykss product ; and we further suggest 

 that a similar remark may apply also to the Beta particles, 

 and^that such slow velocity negative particles may therefore 

 be present in each 0/ the stages of disintegration. This supposi- 

 tion would remove the difficulty which some feel in conceiving 

 of the production of a positive particle without a negative one 

 being simultaneously generated. 



ZOOLOGICAL. 



By R. Lydekker. 



The Late Dr. W. T. Blanford. 



Zoologists and geologists throughout the world will hear 

 with unfeigned regret of the death of Dr. William Thomas 

 Blanford, C.I.E., F.R.S., which took place at his residence in 

 Campden Hill, London, on June 23. after a brief illness, in 

 his 73rd year. Dr. Blanford was on the staff of the Geological 

 Survey of India from 1855 till 1S82, retiring with the rank of 

 Senior Deputy Superintendent. He was a gold medallist of 

 the Royal Society and aWollaston Medallist of the Geological 

 Society, and had been President of the latter body as well as 

 of the Asiatic Society of Bengal. During his Indian service 

 he was attached as naturalist to the Abyssinian Expedition 

 under Lord Napier, and later to the Persian Boundary Com- 

 mission under Sir F. Goldsmid. Of late years he had devoted 

 himself largely to the study of the geographical distribution 

 of animals and of the changes in the configuration of the 

 earth's surface which have had so much to do with the same. 

 Among his important works may be mentioned the " ^Zoology 

 and Geology of Abyssinia," the " iJoology and Geology of 

 Eastern Persia," the " Manual of the Geology of India," 

 written in collaboration with the late Mr. H. B. Medlicott ; 

 the Mammalia and the Geology of the Second Varkand 

 Expedition, and the volume on Mammals and two of those 

 on Birds in the "Fauna of British India," of which series 

 be was the editor. 



The Origin of Salamanders. 



At the conclusion of an elaborate memoir on the develop- 

 ment of the vascular and respiratory systems of the Australian 

 lung-fish (Ceratodut fosterii, published by the New York 

 Academy (Mem. II., part 4), the author, Mr. W. E. Kellicott, 

 remarks that the main object of his investigation was to obtain 

 evidence with regard to the relationship of the lung-fishes, 

 or Dipnoi, to other groups. " It is impossible to believe," he 

 observes, " that the Amphibian resemblances seen in Ccratodus 

 in the development of the vascular, respiratory, and urino- 

 genital systems, as well as throughout the earlier processes of 



development, are in the nature of parallelisms. In the light 

 of their embryology it is impossible to believe that the Dipnoi 

 and the Amphibia are not closely related, and that they have 

 not travelled for a time along the same path at some period 

 during their history." If this view is to be accepted, we must 

 apparently regard the early lung-fishes as the direct ancestors 

 of the extinct primeval salamanders, or labyrinthodonts. 

 A further inference would seem to be that the gills of modern 

 salamanders (which in certain kinds are retained throu,t;hout 

 life) are directly inherited from fishes, and not, as h.is been 

 suggested by some, a new and independent development. 



A New Group of Extinct FLeptiles. 



In a recent issue of the Memoirs of the California Academy 

 of Sciences (Vol V., No. i) Mr. J. C. Mcrriam describes a 

 group of extinct marine reptiles from theTriassic (L'pper New 

 Ked Sandstone) deposits of California, which he regards as re- 

 presenting a new order, the Thalattosauria, typified by the 

 genus ThaUittosanrus. In many respects these reptiles re- 

 sembled the ichthyosaurs, or fish-lizards, having the eye simi- 

 larly furnished with a ring of bony plates. They are, however, 

 broadly distinguished by the upper temporal region of the 

 skull, which has an upper and a lower bony arch, and likewise 

 by the character of the dentition, which takes the form of 

 flattened, crushing teeth, some of which are situated on the 

 palatine and vomerine bones. From these and other features 

 the thalattosaurians appear to be most nearly allied to the 

 rhynchocephalians, as represented at the present day by the 

 New Zealand tuatera (S/'lienodoii), to which they appear to 

 present the same kind of relationship as is borne by the extinct 

 sea-serpents (Pythonomorpha) to the lizards. If this be so the 

 Thalattosauria might perhaps be best regarded as a sub-order 

 of Rhynchocephalia. He this as it may, the special interest 

 attaching to the group is the evidence it alTords of the inde- 

 pendent adaptation of yet another type of reptile to the exigen- 

 cies of a marine existence, and this, too, at an early period of 

 the earth's history. 



The Origin of Mammals. 



In a paper communicated to the March issue of the Zoolo- 

 gischer Anzeiger, Dr. Sixta, of Bohemia, discussed the evidence 

 at present available with regard to the ancestry of mammals 

 and fully endorses the view of those who hold that the group 

 is directly descended from reptiles, and has no near kinship 

 with amphibians. As regards the earlier stages of develop- 

 ment, Dr. Sixta points out that the Australian duck-bill, or 

 platypus, on the one hand and reptiles on the other are inti- 

 mately related ; the resemblance, in all stages of develop- 

 ment, being most significant when the duck-bill is compared 

 with the chclenian group (turtles and tortoises). The chief 

 features in this resemblance were, according to Dr. Sixta, 

 noticed independently by himself and by Dr. Mill, of Sydney, 

 as the result of different modes of investigation, anil may 

 therefore be regarded as well-founded. That reptiles were 

 the direct ancesters of mammals is now, in the author's 

 opinion, an ascertained fact. 



Papers Rea.d. 



At the meeting of the Zoological Sotiety, on May if). Mr. O. 

 Thomas described a new South African golden mole. Mr. 

 F. E. Beddard contributed a paper on the cranial arterial 

 system of birds and reptiles. Sir H. H. Johnston criticised Mr. 

 Rothschild's views with regard to the classification of man-like 

 apes, while Mr. K. Andersen discussed certain kinds of horse- 

 shoe bats. On behalf of Dr. E. Bergroth, a communication 

 was read on the siridulating organs of certain hemiplerous 

 insects. Dr. P. C. Mitchell discussed the anatomy of the 

 Limicolina birds, and Mr. R. I. Pocock redescribcd the 

 Hainan gibbon. .\\. the final meeting of the session on June 6, 

 Col. C. Delme-Radellffe gave an illustrated account of the 

 natural history of West Uganda. Mr. M.Jacoby described new 

 forms of (lidionychis. Dr. Mitchell discussed the mammalian 

 intestinal tract. Dr. H.Gadowreada paperon the distribution of 

 Mexican amphibians and reptiles. Mr. G. A. Boulenger descri- 

 bed new reptiles collected by Dr. Gadow, and also new reptiles 

 and amphibians from South Africa. Mr. Beddard referred to 

 features in the anatomy of certain lizards. Mr. R. Assheton 

 reported on the development of the spiny mouse. The Rev. 

 S. Gorham described new South African beetles, and Baron 

 F. Nopcsa discussed the position of one of the bones in the 

 skeleton of Diplodocus. 



