540 



NATURE 



[November io, 192 i 



Indian Land Mollusca. 



I AM sorry that my oiler of the Indian ©{.terculate 

 land-snails in the collection of the Indian Museum 

 did not reach Sir Arthur Shipley. The offer had the 

 support of the Government of India, which wrote 

 strongly to the India Office as to the unfortunate 

 effect of publishing Mr. Gude's volume without refer- 

 ence to the Indian Museum collection. 



I fail, however, to see what the war has to do with 

 the case, and prefer to ignore Sir Arthur Shipley's 

 motive in his attempt to introduce it in his letter in 

 Nature of October 27 (p. 271). The volume in ques- 

 tion was published in 192 1, and was, I understand, 

 completed shortly before it was published. I received 

 official information that it was in active progress 

 from the Education Department of the Government 

 of India only in the latter part of last year. My 

 offer was made in reference to this communication 

 through the channel through which I had received it. 



N. Annandale. 



Royal Societies Club, S^ James's Street, S.W. 



Curiosities of Nomenclature. 



At Section D of the British Association in two 

 successive years I asked for an explanation of the 

 generic name Calymene, without obtaining it from 

 a roomful of zoologists. On the second occasion I 

 suggested, among other guesses, the remote possi- 

 bility of a derivation from the Greek word K(KaKv\nxivr]. 

 Since then, while consulting Buckland's Bridgwater 

 Treatise of 1836 for quite another purpose, I have 

 found (vol. I, p. 371) a footnote on genera of Trilo- 

 bites giving '"Calymene, from feKaXv/njaeVT;, concealed," 

 with Buckland's comment that such names were 

 "devised expressly to denote the obscure nature of 

 the bodies to which they are attached." 



Nearly half a century after the date of Brongniart's 

 genus the American carcinologist Packard named a 

 genus Caecidotaea (if I may trust Scudder's " Nomen- 

 clator Zoologicus," vol. i, p. 52, and vol. 2, p. 47), 

 thus implicitly assigning his blind isopod to the family 

 Idoteidae in the Valvifera away from its proper place 

 among the Asellidae. Harger in 1878 spells the name 

 Coecidotea (U.S. Fish. Comm., part 6, p. 314). Now 

 Dr. Tattersall, with the spelling Caecidothea (Mem. 

 Asiat. Soc. Bengal, vol. 6, p. 417, 192 1), records a new 

 species of the genus from a shallow domestic well in 

 Japan, and observes that "this species is distinguished 

 at once from all the other species of the genus bv the 

 presence of distinct, though very small, eyes." Thus 

 we have in Packard's professedly blind Idoteid genus 

 a species which is not an Idoteid and which is not 

 blind. Apart, however, from obvious misnomers, the 

 endeavour to pack a budget of information into a single 

 descriptive name must often fail, because it cannot be 

 foreseen that any character noted in the generic name 

 will prove of more than specific value. 



T. R. R. Stebbing. 



Ephralm Lodge, The Common, Tunbridge 

 Wells. 



The Flight of Thistledown. 



Prof. Miles Walker's letter in Nature of 

 October 20 recalls an incident observed during a 

 holiday in the Cheviots in June last which may 

 possibly be of interest in connection with his inquiry. 



It was June 24, the hottest day of the year up to 

 that date, and with brilliant sunshine. The air was 

 comparatively still but for the quivering due to the 

 heat, and there was no distinct current. Our atten- 

 tion was arrested by what to all appearance w^as a 

 dragon-fly hovering 5 or 6 ft. from the ground, and 



NO. 2715, VOL. 108] 



frequently darting a foot or two away. This went on 

 for probably a minute or two, until, in fact, we 

 caught the object for the purpose of finding out 

 what it was. It proved to be a thread of thistledown 

 or something akin to it, and probably an inch and 

 a quarter or more in length. 



It was, perhaps, an insignificant occurrence, but 

 the effect was certainly curious and striking. The 

 tiny film very effectually simulated the flight of a 

 dragon-fly, and would, I think, have deceived all but 

 a practised observer. Whatever current there might 

 be was negligible, and the movement — or the 

 stationary quivering attitude — seemed quite indepen- 

 dent of it. W. E. Lishmax. 



73 Osborne Road, Newcastle-upon-Tyne, 

 October 28. 



The rising of plant-down on calm, sunny days as 

 described by Prof. Miles Walker in Nature of 

 October 20, p. 242, has also been noticed by me occa- 

 sionally. i3ut could not the upward motion be ex- 

 plained by an upward current of air? We know that 

 the air is usually full of eddies on a hot afternoon. \n 

 order to prove that the thistledown moved through, 

 instead of with, the air, it would be necessary to make 

 simultaneous and contiguous measurements of air- 

 motion by means of smoke or of some very special 

 anemometer. It would be interesting to learn if 

 anyone has tried such an experiment. 



Lewis F. Richardson. 



Westminster Training College, S.W.i. 



Ceratium and Pedalion. 



In recently announcing (Nature, September 8, 

 p. 42) the finding of Ceratium in this district, I 

 assumed, on the authority of Kent's " Manual of the 

 Infusoria," that the species was C. fiirca. By the 

 kindness of Herr Lektor E. Jorgensen, author of a 

 monograph on the genus Ceratium, who has examined 

 some specimens, I am now enabled to correct the 

 impression unwittingly given by mv letter, and to state 

 that the forms found by me are varieties of Ceratium 

 hirundinella. My error is, perhaps, a pardonable one 

 in view of the marked differences between the actual 

 organism and Kent's illustration of C. hirundinella, 

 and the general correspondence of the specimens: 

 found with his description, etc., of C. furca. ^ 



With regard to Pedalion mirum, no information has 

 yet reached me that this rotifer has, during the past 

 thirty-two years, been found at places in Great Britain 

 other than the three mentioned in Hudson and 

 Gosse's work on "The Rotifera." 



A. E. Harris. 



44 Partridge Road, Cardiff, October 20. 



Muscular Piezo-electricity? 



The well-known "action current" of muscle car* 

 have nothing to do with piezo-electricity, since it 

 ma}' reach its maximum before any mechanical change 

 begins. Nor do I see anything to suggest the occur- 

 rence of such electricity in other animal tissues or 

 organs. Mr. Wriothesley Russell (Nature, October 

 27, p. 275) might, however, find plants worth inves- 

 tigating for evidence of it. I directed attentiorr 

 sixteen years ago to the association of crystals with 

 electrical changes in Desmodium gyrans (Proc. PhysioL 

 Soc, July, 1905), and (according to a short notice in 

 Nature for August 11, 192 1) Steckbeck has shown- 

 their association with propagation of stimuli in 

 Mimosa piidica, Biophytum sensitivum, and other 

 sensitive plants. F. Buchanan. 



LTniversitv Museum, Oxford, October 31. 



