JUNE 4, I908J 



NATURE 



lor 



have existed in the age of tlie Chalk, as shown in 

 tJie map at the end of the volume. Three correspond- 

 ing names (Archiplata. Archibrasilia, and Archi- 

 ^iiiana) are proposed for the ancient bosses from 

 which the whole continent of South America appears 

 to have been developed, and are explained according 

 to the author's views in his essay on the palaeogeo- 

 graphy of that region. 



Three chapters of Dr. von Ihering's volume treat 

 of the geographical distribution of river-mussels, and 

 are also of some importance, as the author is a lead- 

 ing authoritv on this subject. Written in 1890, they 

 were translated into English and re-published in the 

 Aezv Zealand Journal of Science. The fresh-water 

 molluscs of Chili show many points of affinity to 

 those of New Zealand, and the author agrees with 

 Captain Hutton's views that in the Lower Cretaceous 

 period a large Pacific continent must have extended 

 from New Guinea to Chili, and sent out a peninsula 

 to include New Zealand. 



Those who are engaged in the study of the dilificult 

 problems presented by palseogeography will do well 

 to consult the memoirs collected by the author in the 

 present volume. 



The Moon, a Popular Treatise. By Garrett P. Ser- 

 viss. Pp. xii + 248; illustrated. (London: Sidney 

 Appleton, 1908.) Price 6s. net. 

 In describing the Yerkes photographs of the moon 

 Mr. Serviss has had a pleasant task, and has per- 

 formed it with pleasing results. The text involves a 

 selenologist, a lady questioner, nnd the excellent 

 photographs of the moon taken on successive evenings 

 throughout an entire lunation bv Mr. Wallace with 

 the 12-inch telescope of the Yerkes Observatory. The 

 author has managed to keep the questions in the 

 background whilst making the answers very lucid 

 and impressive. In an introductory chapter the dia- 

 logue turns on the distance, size, motions, &c., of our 

 satellite ; thenceforward it takes each photograph of 

 the moon in turn, and gives a simple, straightforward 

 account, in popular language, of the various features, 

 introducing, at well-timed intervals, asides on geo- 

 metrical, photometrical, and such-like questions. 

 Then follows a chapter (iv) dealing with some of the 

 larger individual features of the lunar surface, as 

 shown on the large-scale photographs taken by Mr. 

 Ritchey with the Yerkes 40-inch refractor. 



The ' exquisite photographs — well reproduced — and 

 the easily readable text" of this volume should ensure 

 it a welcome from all classes of readers, whether they 

 be astronomers or not. There are twenty-one photo- 

 graphs in the first series and five of the enlarged 

 portions, besides a number of diagrams in the text. 



W. E. R. 



The Apodous Holotliurians. By H. L. Clark. 

 Smithsonian Contributions to Knowledge.^ Part of 

 vol. XXXV. Pp. 231. (Washington : Smithsonian 

 Institution, 1907.) 

 The author of this valuable memoir has had the 

 advantage of studving more than two thousand speci- 

 mens of the species included in the families Synaptidae 

 and Molpodadiidae, and he has taken the opportunity of 

 collecting together in the form of a handsome volume 

 the information we possess concerning all the species 

 of this interesting group. There are three coloured 

 and ten monochrome plates of figures, illustrating the 

 form and anatomy of the different species, of which 

 several are original, and the others copied from the 

 works of Semper, Theel, Skiiter, and other zoologists. 

 Eight new genera are described, and a new generic 

 name is proposed for an old genus. The monograph 

 will undoubtedly be of great service to all those who 

 are interested in the study of the Echinodermata. 



NO. 2014, VOL. 78] 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part 0/ Nature. 

 No notice is taken of anonymous communications.] 



Elimination of Self-coloured Birds. 



Statistical data on the real value of colour markings 

 in the survival of animals in the field are so uncommon 

 that the publication of the following fragment may be 

 excused. 



At the Station for Experimental Evolution, about 300 

 chicks of from five to eight weeks of age on May 10 

 were running at large on a well-cropped pasture about 

 three acres in area. For the most part, within the space 

 of less than two hours, twenty-four of these were 

 slaughtered by three crows which were caught in the midst 

 of their work of chasing and killing the young poultry. 

 -A close estimate of the fowl as they ran at large shows 

 that about 40 per cent, were of a white plumage, 40 per 

 cent, blaclv or nearly so, and 20 per cent, had a pencilled 

 or striped marking more or less like that of the female 

 jungle fowl or ordinary game. The interesting question 

 arose, Was there any elimination on the ground of colour 

 bv the crows? Did any colour favour the escape from 

 observation of any of the chicks? 



Were there no selective elimination, expectation on the 

 ground of chance is that of the twenty-four killed 9-6 would 

 be white, 9-6 black, and about five pencilled. .'Ictually, 

 there were killed ten whites, thirteen blacks or prevail- 

 ingly so, and one coarsely mottled grey and buff. No 

 true pencilled bird was killed ! The killed birds were 

 largelv Leghorns, Minorcas (both good fliers) ; the pencilled 

 birds were partly games (good fliers), but mostly dark 

 Brahmas (poor fliers). The race is not always to the 

 swift ! This fragment, then, so far as it goes, indicates 

 that the self-colours of poultry, which have arisen under 

 domestication, tend to be eliminated by the natural enemies 

 of these birds, and the pencilled birds arc relatively immune 

 from attack because relatively inconspicuous. 



Chas. B. Davenport. 

 Carnegie Institution of Washington, Station for 

 Experimental Evolution, Cold Spring 

 Harbour, N.Y. 



"Barisal Guns" in Western Australia. 



In N.-vture of October 31, 1S95, Sir George Darwin, in 

 a letter on " barisil guns," "mist pouffers," and allied 

 noises, desires all those hearing such to record them from 

 time to time. Recently an instance, which may be of this 

 nature, came under my notice, the only apparent difference 

 being that it was a single noise, and was not repeated 

 several times. 



It happened that in July, 1907, I was dispatched by the 

 Government of Western Australia to a remote portion of 

 the north-west of that State to carry out certain inv;^estiga- 

 tions. We were camped for two months on the Strelley 

 River (lat. 20° S.)— which only runs in flood-time— sixty 

 miles from Port Hedland, and the same distance froni 

 Marble Bar. The situation was a desert " spinifex " 

 plain, with occasional low hillocks of granite boulders, _ and 

 uninhabited, save bv occasional sheep and cattle stations, 

 between the two 'places mentioned. At approximately 

 8.35 p.m., mid-West Australian time, on Friday, August 9, 

 I was lying in the tent when, in the words of my diary, 

 " we suddenly heard a dull roar lasting several seconds, 

 increasing in loudness and then decreasing. Everyone 

 heard it and looked round. The sky was quite clear, and 

 there were no signs of thunder clouds. There was no 

 apparent tremor. I thought the noise came from the S.E., 

 others from the N.E. Some suggested it was the rumble 

 of a herd of cattle galloping over a clay pan with hollow 

 ground beneath, as thev hear similar noises in the 

 Kimberley District CW. Australia). Mr. G. and I wonder 

 if it is due to a volcanic eruption somewhere, as that of 

 Krakatoa was heard not very far from here." Next day 



