Oct. 6, 1881] 



NATURE 



531 



Madeira on June 27 (Nature, vol. xxiv. p. 212, with a 

 sequence on p. 237) describing the extraordinary cloud that 

 appeared there on June 26, alarming all the inhabitants, the 

 typically "oldest " of whom declared they had never seen such a 

 cloud as that before? It was, too, in very truth a most remark- 

 able affair ; and seemed to me only to admit of full explanation 

 as a peculiar case of the earth answering by escape of its 

 interior electricity to the sun ; where, according to my own daily 

 solar diagrams, there had just occurred an outburst of solar 

 spots very nearly over the ends of the solar radii that were then 

 pointing towards the earth. 



Weeks passed on without anything to interfere with, or under- 

 value, that explanation; when lo ! on July 26 (the very same day, 

 curiously enough, of the next month) another cloud appeared 

 over Madeira, of just the same peculiar physical character as 

 that of June 26. " Why," were inclined many visitors to ask, 

 "is this kind of cloud, in spite of the asseverations of the 

 ' oldest ' inhabitants, no very great rarity after all in this part of 

 the world?" There had been certainly thus two cases of it 

 occurring with a very short interval between them ; but never- 

 theless, I was inclined to respect the assertions of the greybeards ; 

 and said, "Something unusual must again have happened in 

 the sun; but as my observatory was dismantled on July 23, and 

 the component parts of it packed up ready for shipment on July 

 25 and 26, I had not then any knowledge of what it might be." 

 Now, however, see how perfectly Mr. Hennessey's Indian solar 

 photographs fulfil all that was required to make this second 

 Madeira cloud phenomenon an exactly similar cosmical case to 

 that of its mensual predecessor ; or to testify that an extraordinary, 

 unusual, most su Iden outbreak of solar spots did take place over 

 the very part of the sun's surface turned towards the earth late 

 on July 25, and within twenty-four hours afterwards the earth- 

 electric cloud made its appearance above Madeira, where it was 

 thus noted in my pocket journal : — 



" Tuesday, July 26. — During this afternoon there was a great 

 cloud-structure formed to the west, with all the characteristics of 

 smooth-rimmed lenticular strata under strata, and the topmost 

 visible one breaking out into fringes of cirro-cumuli, that marked 

 the still grander cloud of June 26." This one was however very 

 splendid after sunset, and ^\•hen the red tints thereof had faded 

 from it they were replaced by the richest and purest browns, of 

 the burnt-umber variety, I have ever beheld in the sky. The 

 cloud was vertical over the lower southern sloiies, almost the 

 southern sea-shore of Madeira ; not over the high peaks of the 

 island, in so far at once pointing to a different origination from Dr. 

 Muirhend's (of Cambuslang) cloud in N.\TURE, vol. xxiv. p. 237. 

 That cloud was an affair plainly of the cold of a snow-covered 

 mountain-top in Britain, and is ju^t such an ordinary local pro- 

 duction as any one can see for a large part of the year on the 

 South African hills round about Table Mountain and Table 

 Bay — whenever the southeast ti-ade-wind blows over that counti'y. 

 For there, day after day, it produces very clumsy-shaped masses 

 of vapour either on, or vertically over, the tops of the hills, 

 according to their respective absolute elevations. But never 

 once, during ten years, did I see any approach in the arrange- 

 ment of the constituent particles of those clouds to the neat, 

 refined, peculiar shapes of what formed the most conspicuous 

 characteristic of the two successive Madeiran earth-electric clouds 

 of June 26 and July 26. They had each been preceded by as 

 peculiar, as rare, a central outburst of solar activity, and probably 

 required no less for their due manifestation, as well as the per- 

 formance of their functions in cosmical electric radiations and 

 exchanges. PiAzzi Smyth, 



Astronomer- Royal for Scotland 



15, Royal Terrace, Edinburgh, September 30 



American Cretaceous Flora 



I HAVE only just read Prof. Newberry's clear and concise 

 account of the American Cretaceous series (Nature, vol. xxiv. 

 p. 191). I regret that I am still unable to agree with him that 

 the relative ages of American and European Cretaceous beds 

 are satisfactorily correlated. I should not again venture to insist 

 so strongly on what must seem to Dr. Newberry to be but an 

 individual opinion, except that he seems to expect a reply, and I 

 have further some new evidence to bring forward. Of my 

 opinions the one to which he takes mo-t exception seems to be 

 that "no American or European so-called Cretaceous land flora 

 can be proved to be as old as our White Chalk." It is this 

 statement therefore which I must substantiate. 



In America the plant -beds of Vancouver's Island contain many 

 Angiosperms, and are said to be of the age of the Gault or Upper 

 Greensand, and the Dakota group, which has yielded one hundred 

 distinct species of Angiosperms, is said to be older than our 

 Chalk. The Colorado group is said to represent not only our 

 Grey and White Chalk, but the Miistricht beds. Even the 

 Laramie group or " Lignite series" is placed in the Cretaceous 

 system. I have unfortunately not the books requisite to re- 

 examine critically the American evidence, and must therefore 

 confine myself to stating that which on this side of the Atlantic 

 tends to show the relative age of the American series to be 

 very considerably overe.-timated. I would propose, however, to 

 Prof. Newberry an exchange of the more abundant Cretaceous 

 moUusca, in order that they may be compared together ; after 

 which I might possibly find myself able to vi-it some of the 

 American sections. This I should the more like to do, as I 

 happen to be acquainted both with the Cretaceous and Eocene 

 mollusca, and with the floras, of England — the very evidence, 

 in fact, upon which the respective ages of the series is to be 

 decided. 



In the fir!:t place I am able to assure Prof. Newberry most 

 positively that on plant evidence the Laramie series must be 

 bracketed, if anywhere, with our Middle Eocene. Not only is 

 the facies of the flora identical, but identical species apjiear in 

 both continents in these series. I cannot yet give a list, but I 

 would jjarticularly point to such highly characteristic species as 

 Lygodiuin A'au/fussi, Heer (syn. L. ticiiropt^oides, Lesq.), and 

 Anemia subcrdacca (Saporta) (syn. Cymncgramma tlavdtnii, 

 Lesq.), which were identified by Lesquercux himself after com- 

 parison with actual specimens which I forwarded to him. 

 The.se are fully described in the Pal.-eontographical Society's 

 publications, which I hope Prof. Newbeiry will glance through. 

 We have beyond all question, in the first stage of the great 

 " Lignite series," a common line to work from, and the age of 

 this line is, a-suredly, according to the plants, that of our 

 Middle Bagshot series. Below our Middle Bagshot there is, in 

 France and F.ngland, a va^t series of Eocene deposits containing 

 many distinct floras of most dissimilar types, and about which, 

 in many cases, scarcely anything is known. Even at the base of 

 these wc are very far from the age of our Chalk, we have still 

 an obscure series of local deposits which to some extent bridge 

 the gap between our Secondary and Tertiary periods. Some of 

 the most noted of these deposits I have recently visited. 



The highest, I believe, of these so-called Cretaceous beds in 

 Europe is the coral deposit of Faxoe. Its solitary claim to be 

 considered of Cretaceous age is a Plairolomaria ! It has no 

 Cephalopods except Nautilus and Aturia zic-zag, and not even 

 the persistent Iiioccramus. Except Pleurotomaria, the mollusca 

 are all more of Eocene than Cretaceous type. Cypraas are 

 abundant, and there is a Milra, Triton, Valuta, Turbinella, a 

 Rostellaria and Ampul/aria, &c. 



In the underlying " Faxoelaget " the Cretaceous element is rein- 

 forced by Baculites and Scaphites. In the Greensand of Born- 

 holme, Betcmnitts and Inoceramus are added ; and finally, 

 in the Chalk of Moen, a smooth Ammonite, one or more large 

 Hamites, and a variety of other Cretaceous types appear. We 

 have thus a clear passage downward into the Cretaceous series ; 

 but even the age of the Moen's Chalk is not quite definitely 

 known, for the supposed BcicntnitcUa, which apparently fixed its 

 zone, is in reality a BcUmnite. A few forms, however, seem 

 to link it slightly with the Greensand of Aachen, whose age I 

 shall now consider. 



The highest of the Aachenian series is Chalk with flints. In 

 this mollu-ca are few ; but this is of less importance, since the 

 Chalk rests upon Greensand, in which they abound. Tlie fossils 

 are in much the same condition as at Blackdown, and among 

 them are about sixteen apparently Gault and Blackdown species. 

 The greater part of the latter are however carried up into Jour 

 Grey Chalk, where they cease simply, as far as we know, be- 

 cause the succeeding beds were not fitted to preserve them. 

 These shells are mixed with others, about thirty species, of 

 Tertiary a=pect, including Vohita, Murex, Turbo, Fusus, Pyrula, 

 Borsonia, Bulla, Turritella, Corbula, Tellina, Cythcrca, Lucina, 

 Pcctunculus, &c., and Clavagclla. The presence of Bf lie//! nitilla 

 mucronata and B. quadrata, together with Baculites, also point 

 to its being at least younger than the Lower Chalk. Below 

 these are the sands with Dicotyledons. The flora these contain, 

 while mainly unlike that of the Eocene, possesses nevertheless 

 some types of leaves which appear- identical with Eocene forms, 

 and is of the highest importance in comparing the American 



