22 Wm. Carruthers — Falwohotany of Sweden. 



whole of my collection can be unpacked and settled in its new 

 quarters, so I have thought it better not to delay longer the 

 admission of the one point where I find that I have erred. 



P.S. — The above remarks were written before the October Number 

 of the Magazine, containing Dr. Eoberts' second paper, had reached 

 me. I leave them as they were written, though he appears now 

 to have visited the Port Dinorwic district, and distinctly speaks of 

 felsite pebbles in Anglesea, because his examination of the former 

 does not seem to have been careful enough to show him that the 

 grits become conglomeratic near Tan-y-maes, and 1 do not admit 

 that the question can be settled by the latter. I have not myself 

 been struck with the remarkable resemblance of the conglomerate of 

 Garth Perry to that of Twt Hill, and think that by the method 

 of reasoning here adopted I could prove even the Bangor series of 

 Prof. Hughes to be only Cambrian conglomerate. — T. G. B. 



V. — Contributions to the Paleobotany of Sweden.^ 

 By Wm. Cakeuthers, F.E.S., F.L.S., F.G.S. 



MR. A. G. NATHOEST, whose recent contributions to the Palseo- 

 botany of Sweden have been very valuable, has been turning 

 his attention to the impressions found on the surface of schists, espe- 

 cially in Palaeozoic rocks, which have been too readily accepted as im- 

 pressions of plants. They find a place among the Algee of Schimper's 

 "Traite de Paleontologie Vegetale," and they are employed by 

 Saporta and Marion in their recent work, " L'Evolution du Eegne 

 Vegetal," and are treated as Algae, and employed as data in their 

 account of the evolution of the vegetable kingdom. Mr. Nathorst, 

 so long ago as 1873, called in question the plant origin of many of 

 these markings, and he has recently published in the Transactions 

 of the Eoyal Swedish Academy (vol. xviii. No. 7, Stockholm, 1881) 

 an exhaustive treatise on the subject, with eleven phototypic plates 

 of impressions which he obtained by the motions of different animals 

 or the trails of plants on soft materials. He first experimented with 

 gypsum, getting the animals to move over the surface while it was 

 soft, and securing the permanence of the tracks by the hardening of 

 the gypsum. This method was satisfactory with the smaller 

 Crustacea, but annelids and molluscs moved so slowly that the 

 gypsum hardened before they crossed it. And, besides, it was not 

 possible to experiment in this way with some marine animals, for 

 the fresh water with which the gypsum was mixed at once killed 

 them. The earlier plates are devoted to the impressions produced 

 on the soft gypsum. The results are remarkably like the Arthro- 

 phyciis and Crossochorda of the Silurians. These impressions have 

 been produced by the following Crustacea : Corophium longicorne, 

 Fabr., Crangon vulgaris, Fabr., Jcera albifrons, Leuck., Gammarus 

 locusta, Linn., and IdotJiea baltica, Pall. The markings made by 

 the Idothea are singularly like the impressions of a Lycopodium, or 

 of some branching sea- weed, like Caulerpites, Sch. 



1 Om Sp^r af NS,gra evertebrerade djur MM. Och Deras Paleontologiska 

 betydelse, af A. G. Nathorst, med 11 Taflor, 4to. pp. 60. 



Kougl. Svenska Vet. Akad. Haudl. Band. 18, No. 7. Stockholm: 1881. 



