May 17, 1883] 



NATURE 



53 



of the sandstones. Both Dr. Dawson and Dr. Linnarsson 

 therefore l»ng ago expressed the opinion that the Bilobites of 

 Sweden and America must have been trails of some animals. 

 In order to explain this mode of occurrence so that it might not 

 appear as proof against the vegetable nature of the bodies, 

 Saporta takes refuge in a somewhat curious manner of fossilisa- 

 tion described and illustrated by woodcuts in the review referred 

 to. As I feel sure that every one who has made himself ac- 

 quainted with true modes of fossilisation will immediately be 

 aware that the process adopted by Saporta is indeed most 

 improbable, it will be superfluous to dwell any longer on that 

 question. But even granted that the plants sometimes should 

 occur in this way — which s'atement I, however, think must be 

 due to some confusion as to the real facts — such an occurrence 

 could never be regarded but as a very rare exception to the 

 general rule. And it therefore does not explain why the Bilo- 

 bites should only occur in this, for true plants, exceptional way, 

 (on the under surfaces of the slabs), never as true fossils em- 

 bedded in the rock. This mode of occurrence harmonises, on 

 the other hand, perfectly with the view that the Bilobites are 

 trails of some animals, while it cannot be explaned on the 

 supposition that they are true o ganic bodies. 



One arrives precisely at the same conclusions on studying their 

 external structure, which possesses pretty great analogies as well 

 with the trails of Limulus, long ago described by Dawson, as 

 with those of other Crustaceans, described by myself. It is true 

 that Saporta lays great stress on some superficial markings which 

 are to be seen on some of the French specimens ; but those who 

 have studied not only the French Bilobites, but also those from 

 Sweden or America, will soon be aware that the markings re- 

 ferred to are quite accidental. It is indeed surprising that 

 Saporta, while adopting my views concerning Cross ichorda, 

 does not see that the Bilobites are somewhat analogous forms, 

 th mgh much larger. There is consequently no reason why 

 they should be regarded as other than the trails of Crustaceans. 



As for Eophyton, it is a pity that this should still be men- 

 tioned as possibly of organic origin. It occurs precisely as true 

 trails on the under surface of the slabs ; it is found in every 

 system from the Cambrian to the present time, where it can still 

 be studied on the seashores ; all the different forms, under which 

 it presents itself are also still to be seen there. Although it thus 

 has been proved that it cannot be any organism, Saporta still 

 adheres to the opposite opinion. Now, if he had read through 

 -my work, he would have learnt that I by experiment have de- 

 monstrated that Eophyton can not only be produced by drifting 

 plants, but also by the tentacles of Medusae or other soft bodies. 

 Now there are casts of Medusae associated with Cambrian 

 Eophytons of Sweden, and their habits were probably--as I 

 have elsewhere l tried to show — similar to those of the existing 

 Polyclonia frondosa, which creeps on the mud by means of its 

 tentacles, and it is therefore likely tlat the Cambrian Eophytons 

 are of this origin. 



It is further stated that "the Chondrites of the Flysch, 

 strongly impregnated as they are with carbonaceous matter, are 

 admitted on all hands to be Algae, and the author asks how the same 

 origin can be denied to casts of specifically identical Chondrites of 

 the Cretaceous and so on to the Liassic forms." This argument 

 is, however, a real " petitio principii," for it is so far from the 

 actual state of things that the Chondrites of the Flysch are on all 

 hands admitted to be Algae, that many authors, and among them 

 Dr. Th. Fuchs, of Vienna, whose excellent and exhaustive 

 studies of the Flysch are everywhere known, hold a quite oppo- 

 site opinion. And as for the supposed carbonaceous matter, it is 

 not much better with this, as will be shown from a communica- 

 tion from Dr. Fuchs published in my work referred to : " The 

 supposed carbonaceous nature of the Chondrites of the Flysch is 

 in ir.y opinion a perfect mistake. They are certainly very often 

 quite black, but even in such cases they consist only of dark 

 marl, not of coal." 



Much more might be said on the fossil Algae, hut as I am 

 about to combat the views held by Saporta more fully in a 

 special work, I will here only add that I have found no state- 

 ment whatever in his work referred to which would tend to alter 

 my opinion, that almost all the "Alga incerta s/dis" in 

 Schimper-Zittel's " Handbuch der Paleon'ologie " are not 

 vegetable fossils. A. G. Nathorst 



Stockholm, April 9 



1 A. G. Nathorst, " Orn aftryck af Medusar i Sveriges Kambriska layer. " 

 (Svenska Vcteushaps Akademiens Handlingcr, Bd. xix. No. 1, Stockholm : 

 Norstedt och Soner, 1881.) 



Dr. Nathorst has certainly shown that many of the mark- 

 ings referred to Algce by some authors might be tracks left by 

 moving animals on a soft mud, but is there reason to suppose 

 that there are conditions under which submarine surfaces f-f 

 very soft mud with minute tracks have, or could ever have been 

 preserved. On the other hand there is no question about sea- 

 weed having existed in Palaeozoic and Mesozoic times, and either 

 some of the markings in question are their prints, or no traces of 

 them are preserved. Now it is anuncontroverted fact that even 

 the most indestructible of all vegetable tissue, tint of the 

 Coniferae, has been met with in the same condition of fossilisa- 

 tion, i.e. a projecting cast in sandstone on the under side of a 

 slab, and without any internal trace of tissue or even of colouring 

 due to carbon or iron, and Sap rta lias offered a satisfactory 

 explanation of the origin of such casts. From the relative rarity 

 with which terrestrial plants have been thus preserved, Nathorst 

 almost derides Saporta's application of this explanation to fossil 

 Algae, yet it is by no means improbable that this may be their 

 normal mode of preservation. The decay of dead olive-green 

 seaweeds in water must be very rapid. The decomposition of some 

 among them sets in almost immediately under water, and a c dour- 

 less mucilaginous fluid is given off copiou-ly. I have not watched 

 the whole process of decay, but my impression is that the entire 

 substance in some species would eventually pass away in a 

 structureless glairy mass, and therefore that nothing but a hollow- 

 impression could ever be preserved. Casts of these would be 

 more likely to be preserved in sand or mud than mere tracks, 

 because the substance of the weed would occupy them, and 

 prevent them from being immediately filled with the same 

 quality of matrix as the suit unding rock, and until wrat would 

 afterwards be a line of cleavage had been produced. So far 

 therefore from its being exceptional for fossil seaweeds to 

 appear as cats projecting from the under surface of the over- 

 lying mud, this is likely to be the normal condition in which 

 fossil alga; are preserved. This is apart altogether from the 

 question whether any of the Palaeozoic markings are Alope, for, 

 these differ so considerably from any existing forms, that in the 

 absence of internal structure it is quite unlikely that there will be 

 any general agreement respecting them. Thee ob-ervations do 

 not apply to the Rbodospermeae, which scarcely enter into the 

 question. Some simple experiments on the decay of seaweeds in 

 fine sand under water, which any one at the seaside could make, 

 would help to throw light on the suhject. J. S. Gardner 



The Weather and Sunspots 



In Nature (vol. xxvii. p. 551) Mr. Williams ascribes the great 

 cold of March, 1883, at the Riviera, to the absence of sunspots. 

 There is the less reason for ascribing this cold to sunspots, as till 

 now much more evidence goes the other way. And may it not be 

 contended that this evidence is in favour of warm weather, with 

 minimum sunspots in the tropics or in summer alone. The 

 months of November to March, 1877-78, especially February 

 and March, were so warm over an extensive area, especially in 

 the interior of North America and Western Siberia, that the 

 mean temperatures were nearly without precedent, while in no 

 extensive country of the world the temperature was much below 

 the average. 



I give some data for March, 1874 (a season with a consider- 

 able number of sunspots), at Suchnm-Kale, on the east coast of 

 the Black Sea, a place in the same latitude as Cannes, and 

 similarly si'uated in respect to sea and mountains ; it Li sheltered 

 from cold winds, and much warmer than the surrounding 

 country. 



The observations in Russia being made at 7 a.m. and I and 9 

 p.m., and no minimum-thermometer used, the minima cannot be 

 strictly compared. 



The mean temperatures for a long average at Nizza (which 

 are about the same as at Cannes) are January 47°' 1, March 51° p 8 ; 

 at Suchum-Kale, January 43°'o, March 47°'8, being at both about 

 4° colder. Taking the mean of minimum and maximum as the 

 daily mean at Cannes, and that of 7 a.m. and 1 and 9 p.m. as the 

 daily mean at Sucbum, we have : Coldest days of March, 1883, 

 at Cannes, 10th, mean 35° - 5, or i°°'3 below average; nth, 

 34°'S, or I7°'3 below average ; lowest minimum on the nth, 24°' 1, 

 or 27°7 below monthly mean temperature. Coldest days of 

 March, 1874, at Suchum, 3rd, 19° 9, or 27°'9 below average ; 4th, 

 20° - 5, 27°'3 below average; 5th, 20° - 8, 27°o below average. 

 The lowest temperature at 7 a.m. was, on the 6th, i6° - 4, or 

 31°'4 belnv average monthly temperature. Thus it is seen that at 



