FUCOIDES IN THE COAL FORMATION'S. 321 



plants of the same type, if not of the same kind, as those which we generally consider as 

 characterizing the Chemung group. 



$7. GENERAL DISTRIBUTION OP SOME SPECIES OF FTjl?OIDES IN THE PALEOZOIC 

 AGES AND THEIR VALUE AS CHARACTERS OF SYNCHRONISM. 



The moulds of Fucoidal plants, observed in abundance at the base of the gritty sand- 

 stone which caps the hills at and around Wurtemberg, about the height of three hundred 

 feet in the Coal Measures, represent a species apparently identical with, or at least undis- 

 tinguishable from the large variety of Palceophycus tubularis, Hall. The Fucoides in the 

 shales, inferior to this sandstone, resemble the small forms of the same species and Palceo- 

 phycus irregularis, Hall, which Prof. Goppert considers as a mere variety of it. Now, the 

 remains of marine plants of this kind already appear in the Lower Silurian Calciferous 

 sandstone, and may be considered as representing some of the primordial types of the veg- 

 etable world. The polymorphous Fucoides antiquus of the authors {Buthopteris antiquata, 

 B. gracilis, B. palmata, B. impudica, B. rarnosa, Hall) is common in strata of the Upper 

 Silurian Clinton group ; is especially abundant in the Chemung of Pennsylvania and 

 Ohio, and reappears in the Cretaceous formations of Europe. At least Fucoides Targioni, 

 Brgt., of this epoch, so well resembles in its multiple varieties the different forms of F. 

 antiquus, that it cannot be separated by appreciable characters.* The group of Fucoides, 

 which we have examined in this paper, has representative fossil remains, apparently iden- 

 tical in species, in the whole extent of the Devonian Measures. At least the same form of 

 Fucoides Cauda-galli of the Corniferous period is seen in the Chemung or Waverly sand- 

 stone of Ohio, and is especially abundant in strata scarcely fifty feet lower than the base 

 of the Millstone grit of Southeast Kentucky. It may be that the fossil remains represent 

 different species, for even Caulerpites marginatus, which ascends into the Coal Measures, is, 

 when its border is casually destroyed, undistinguishablc from Fucoides Cauda-galli* But 

 we are authorized from these facts and others of the same kind to conclude that most of 

 the marine Alga?, of which remains are found in the Palaeozoic strata, have had a wide 

 range of distribution. From this, it is contended, perhaps rightly, that they cannot be 

 considered as reliable guides in the determination of geological horizons. 



If this discredit was limited to the remains of marine Algae only, it would perhaps not 

 be worth considering in any way. But it touches, by inference, every kind of fossil 

 plants, and thus tends to eliminate as useless some palaeontological data which are cer- 

 tainly of practical importance. I allude to the remains of land plants, especially the coal 

 plants, some of which may be justly considered as characteristic even of the horizons of 

 the various beds of coal. 



* Geological Report of Pennsylvania, p. 848. Goppert, Fossil Flora des Silurisehen, p. 434. 



VOL. XIII. 41 



