﻿Fucoids of the Cincinnati Group. 



161 



PsilopJiyton gracillimum with this genus, Mr. Walcott goes on to say : 

 "The resemblance of these two species [the two new ones], of Dendrograp- 

 tus to Lycopodiaceous plants of the genus PsilopJiyton is very striking and 

 apt to mislead the observer. Their occurrence with Algae, graptolites, 

 trilobites, and brachiopods in the same layers of shale, in a position indi- 

 cating their position in situ, taken with their graptolitic structure, pre- 

 cludes the idea of their being of other than marine origin." The striking 

 resemblance between specimens of PsilopJiyton gracillimum and Butho- 

 trepJiis gracilis, leads to the inference that they are both the same, and as 

 one has been referred to the Graptolites, the other should be also. Now, 

 in relation to the varieties of Dendrograptus (Buthotrephis, PsilopJiyton) 

 gracillimum, as it should be called, it might be supposed that specimens 

 with wide and divergent branches would belong to other species. But it 

 is well known that all the varieties run, as it were, into each other, so that 

 no clear line can be drawn between them. Further, Lesquereux has de- 

 scribed a species of PsilopJiyton under the name of P. cornatum, which is 

 probably the same as Hall's variety, intermedia. It seems, therefore, in 

 the opinion of the writer, as if all these species and varieties should be 

 placed under one name, that of Dendrograptus gracillimum, the name 

 gracilis being preoccupied. 



Dendrograptus gracillimum, Hall. 

 (Buthotrephis gracilis, Hall). 

 (Psilophyton gracillimum, Lesq.). 



var. intermedia, Hall. 



(Psilophyton cornutum, Lesq.). 



var. tenuis, Hall. 



(Buthotrephis tenuis, Hall). 



var. crassa, Hall. 



var. flexuosa, Hall. 



(Buthotrephis flexuosa, Hall). 



Genus Lockeia, James. 1879. 

 The genus Lockeia was proposed in the Palaeontologist, p. 17, by U. 

 P. James for certain oblong bodies found lying on the surface of rocks 

 from a certain horizon of the Cincinnati group. They were likened in 

 form to grains of wheat, and were supposed to be parts of ancient Algse. 

 (Plate 9, figure 7.) From the study of these forms, and from the resemblance 

 they bear to fossils found in other groups, it is likely that in this fossil, 

 long referred to the Algae, is to be found, what have been called by Hall, 

 Nicholson, and others, the "ovarian capsules" of species of Graptolites; 



