Sept. 3, 1874J 



NATURE 



355 



and atolls ? Mountains of different heights are now more 

 or less submerged, and either capped with vast thicknesses 

 of coral, or their tops are girt with barrier and fringing 

 reefs. Take away the sea and the coral growth, and 

 imagine the conditions which prevailed during the slow 

 piling up of these volcanic rocks, their denudation and 

 final overwhelming by the inrush of the ocean incident 

 to the first phase of subsidence. Little is known con- 

 cerning the age of the raised reefs of the Pacific, and 

 therefore of the duration of the existing state of things ; 

 but in the Caribbean there have been reefs in consecutive 

 ages since the early Cretaceous period, and in that area 

 there have been during past ages subsidences and up- 

 heavals with contemporaneous volcanic action, following 

 the same laws as those so elaborately described by Darwin 

 as influencing coral growth in the Pacific. 



P. M. D. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself respojisible for opinions expressed 

 by his correspondents. No notice is taken of anonymous 

 communications .] 



The Long Peruvian Skull 

 It was not my intention to have replied to Dr. J. B. Davis's 

 letter on " The Long Peruvian Skull " in Nature, vok x. p. 123, 

 as I shall have an op|iortunity before long of presenting the sub- 

 ject in detail before scientific readers. I find, however, by letters 

 from England that an answer is expected from me. To me, it 

 seemed little more than a reiteration of his disbelief in the exist- 

 ence of such a type ; while it leaves unnoticed what I specified 

 as the main point in the discussion. 



Dr. Davis demands the production of "half a score of ancient 

 Peruvian dolichoceplialic skulls, the appearance of which totally 

 precludes the possibility of interference by art, or other deforming 

 process." Had an anonymous correspondent so stated the issue, 

 I should have supposed that the writer had never seen half a 

 score of Peruvian skulls in his life. The collection presented by 

 Mr. Hutchinson to Prof Agassiz numbered 368 ; and out of this 

 Prof Wyman reports only ehi'eii not flattened or distorted. Is 

 Dr. Davis prepared to rule the remaining 357 out of court as of 

 oo value in relation to his brachycephalic type ? Tliis question of 

 Peruvian long and short heads must be settled in connection with 

 a deforming element affecting both types, or it cannot be settled 

 at all. Hence my specification of the real issue. Keeping this 

 in view, I must beg leave meanwhile to refer, for the sake of 

 brevity, to my statements in Nature, vol x. p. 48, in reference 

 to examples jireviously adduced ; while I now point out others 

 easily accessible to Dr. Davis. 



The large collection furnished to Prof. Agassiz was obtained, 

 apparently at one time, from a single locality, " Ancona and its 

 neighbourhood." Hence no doubt the uniformil/ of type. 

 Doubling this number of skulls from the same locality would add 

 I nothing to the evidence. It is otherwise with the London Anthro- 

 pological Institute. Its collection was obtained at different 

 1 times, partly from the same accessible locality ; but also from 

 ' Santos, lea, Passamo^o, and Cerro del Oro. These include 

 ' places hundreds of miles apart ; and Prof Busk, after minute 

 I study, reports that the evidence of the existence of a dolicho- 

 I cephalic type afforded by the collection, though "not very 

 I abundant, is ne^rrlkelcss decisive.'" 



I It is a case precisely analogous to the remarkable dolicho- 

 I cephalic British type recognised by the acute sagacity of the 

 late lamented Dr. Thurnam, in the Uley, Kennet, Littleton 

 i L)rew, Rodmarten, and other long barrows in Wiltshire, &c., as 

 illustrated in the Crania Britaiinica, for which so great a debt 

 of gratitude is due to Dr. Davis and his gifted colleague. Those 

 dolichocephalic skulls are exceedingly rare ; they are found along 

 with brachycephalic skulls ; but, as Dr. Thurnam showed, 

 accompanying elements suggestive of the latter as an inferior or 

 servile class. Long ago, in a paper in the Canadian fournal of 

 September 1S62, I referred to the analogy this presents to the 

 long Peruvian skull mingling in the ancient Inca cemeteries 

 with crania of a markedly diverse type. 



No multiplication cf specimens of the less rare brachycephalic 

 skull of the British cist or round barrow will invalidate this ex- 

 ceedingly rare but valuable dolichocephalic British type produced 

 by Dr. Thurnam ; and the exhibition of a whole ship's cargo of 

 brachycephalic skulls from the accessible coast cemetery of Ancona 

 is equally ineffective in disproof of the rare Peruvian dolicho- 

 cephalic skull of Titicaca and other ancient burial-grounds. 



Dr. Davis refers to an error in one of the woodcuts of my first 

 edition of " Prehistoric Man." To anyone conversant with the 

 difficulties of a Canadian author correcting proof-sheets for the 

 London press, the chances of error, with proofs passing while 

 the woodcut swere in the engraver's hands, and their mere titles 

 or blank spaces in lieu of them, must be obvious enough. Dr. 

 Davis will find the error pointed out in the preface to the second 

 edition. 



University College, Toronto, Aug. 6 D.\NIEL Wilson 



Pollen-grains in the Air 



I AM very sorry to find that, owing to my absence from home 

 at the time, a question addressed to me by Mr. A. W. Bennett, 

 in Nature, vol. ix. p. 4S5, has escaped my notice hitherto and 

 remained unanswered. Mr. Bennett, alluding to my letter on 

 " Microscopic Examination of Air " (N.vture, vol. ix. p. 439), 

 asks on what ground I refer the " triangular pollen " captured 

 on my slide to the birch and hazel. The identification resulted 

 from comparison under the microscope. The pollen-grains 

 which I obtained from catkins of birch and hazel exhibited three 

 conspicuous equidistant prominences (pores) giving each grain a 

 triangular appearance. I cannot now remember if this appear- 

 ance was equally distinct before and after immersion in glyce- 

 rine : probably there was a change of shape due to osmosis. I 

 confess that I used the word "triangular" not in its strict 

 geometrical meaning, but in order to mark a feature which dis- 

 tinguished the pollen-grains of birch and hazel from those of 

 poplar. Referring to my notes, I must admit that the shape of 

 the grains which I identified with birch pollen ^^-oukl have been 

 more accurately described as "spherical with three large pro- 

 tuberances." IIUEERT Airy 



Blackheath, S.E., Aug. 31 



Chrysoraela Banksii 



I SHOULD be much obliged if you would allow me to ask the 

 following question of Coleopterists in the columns of Nature : — 



Does Chrysomela Banksii possess any quality, such as that of 

 exuding an acrid liquid or the like, which would be likely to 

 make it distasteful to spiders or other animals? I have seen it 

 first taken and then rejected unharmed by a Trap-door Spider, 

 and as these spiders feed largely on beetles, I am led to suppose 

 that this particular beetle has some special protection. 



J. Traiierne Moggridge 



2, Foxton Villas, '^Richmond, Surrey, Aug. 27 



The Aurora Borealis 



M.\Y I ask the readers of Nature for information on the 

 following points : — • 



1. Where can I find references to any observations on the 

 polarisation or otherwise of auroral light ? 



2. Are there any published lists of aurora; arranged with a 

 view to determine the periodicity of its recurrence ; or, if not 

 so arranged, sufficiently extended for such an investigation ? 



3. Has any observer besides Mr. Backhouse noted the rela- 

 tive proportion between eastward and westward movement of 

 auroral rays? Henry K. Procter 



North Shields, Aug. 29 



ROBERT EDMOND GRANT, M.D., F.R.S. 



ON Sunday, August 23, after an illness of about a 

 fortnight, died Dr. R. E. Grant, for many years 

 Professor of Zoology and Comparative Anatomy at Uni- 

 versity College, London. The family from which Dr. 

 Grant was descended had its head-quarters in the county 

 of Elgin, whence his father removed to Edinburgh, 

 settling as an accountant and a writer to the signet in 

 Argyll Square. He was one of fourteen children, twelve 

 brothers and two sisters, being the seventh son, and the 



