^°189l)!"'] PROCEEDINGS OF THE NATIONAL MUSEUM. It 



that is explained the appearance of the irregular flexnons filaments 

 covering the surface of the cortex of the tubes of the GyroUthes of 

 Saporta and also of those of Cylindrltes striatus described above. 



These remarks in support of my belief in the vegetable nature of 

 these bodies are not conclusive. Indeed, no positive proof that the 

 so-called problematic organisms represent fossil Algce can be furnished 

 except by a microscopical analysis of their texture. But the Algfe are 

 cellular plants, rapidly destroyed by maceration, and therefore their 

 tissue is rarely preserved by the penetration of mineral elements, as it 

 is, for example, by the silex in the fossil ization of vascular plants. It 

 is for the same reason that remains of algse, even in accumulation, can 

 not be transformed into coal, and that as fossils they do not show, except 

 in rare peculiar cases, traces of coally matter; for the cellular com- 

 pounds of their tissue is, by decomposition of the plants, disseminated 

 as bituminous fluid even under the same circumstances of slow burn- 

 ing, wbich gradually transforms the woody or vascular tissue into coal. 

 In rare cases only the bituminous elements of the Alg(e become fixed 

 and solidified. It is, where marine plants of thick tissue or in massive 

 agglomeration become embedded, decomposed, and flattened in com- 

 pact argillaceous or clayey materials, impenetrable to the fluid pro- 

 duced by decomi)osition of the plants. The bituminous elements arc 

 then gathered in the space formed by the stratification of the clayey 

 materials and then gradually solidified and crystallized into a vitreous 

 hard black matter, ])ure compact bitumen, much like hard coal. Thin 

 sheets of this matter are often observed in the formation of black shales 

 of the Devonian, sometimes appearing like black spots of different 

 forms, generally as thin as paper and adhering to the shale, sometimes 

 like circular groups of sporangia, more rarely as layers of concrete bi- 

 tumen, and of a thickness of 2 or 3'"'", adhering by one side to the 

 shale vertically split by cleavage into cubical pieces more or less dis- 

 tantly separated from each other. This crystallized bitumen is some- 

 times attached to a flat surface apparently like a piece of bark, traced 

 by thin vertical lines, irregular in distance, but parallel, even sometimes 

 crossed at right angles by a few other straight strine, probably repre- 

 senting traces of some kind of superficial organization of stems of Algce,. 

 but none, as far as I know, distinct or regular enough to offer reliable 

 characters for determination. These flat surfaces, diversely striate, are 

 comjjarable to the problematic organism figured as Vexilliitn or Eophyton, 

 mentioned above. 



In cases like this the fossilized bitumen sufficiently proves that these 

 traced surfaces, like the round groups of sporangia, represent marine 

 organisms; but their reference to peculiar groups, genera, even fam- 

 ilies of algic, remains hypothetical. 



Habitat. — Portage group, in cliffs bordering Lake Brie, near Cleve- 

 land, Ohio. Collector, Rev. H. Herzer. 



