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Cincinnati Society of Natural History. 



There can scarcely be a doubt but that this species is the burrow of some 

 sort of annelid. The rugose surface would be caused by the irregularly 

 thrown up mud ; the flexuous stem and the branching, by the windings of 

 the worm. Burrows precisely like the specimens of this fossil have been 

 noticed by the writer on muddy banks of the Little Miami River, and all 

 facts point to the conclusion that instead of its representing the remains 

 of an Alga, it is an ancient burrow. 



The different appearance presented by the complete burrow and the 

 same one with the top taken off, exposing the excavation, has been referred 

 to, and in P. tubularis is to be found the P. rugosus, treated in this way. 

 In other words, P. rugosus represents a complete burrow and P. tubularis 

 one of the same sort, showing the hollow instead of the ridge. 



P. simplex, Hall, with simple, cylindrical, flexuous stems, with the sur- 

 face smooth or rough, can be referred to the same source as the preceding 

 two species, and was likely made by the same animal form. Certainly the 

 characters distinguishing the tubularis and the simplex are insufficient to 

 separate them. 



P. virgatus, Hall, described from the Hudson River group of New York, 

 was found in the spring of 1884, by the writer, near Ludlow, Kentucky. 

 The specimens were about an inch wide, and about eight inches long, of 

 the same width their whole length, were slightly curved, and overlying 

 one another in various directions. It is difficult to imagine what this fossil 

 could have been, though it is not likely that it was a plant. It is more 

 like the impression of a large Solen thaa anything else. 



Genus Trichophycus, M. and D. 1878. 



This genus, established by Miller and Dyer, in Journal of Cincin- 

 nati Society of Natural History, Vol. L, p. 24, has included three 

 species, of which T. lanosum was the type. Two of the species, T. venosum 

 and T. sulcatum, have already been referred to under mud markings 

 (this Journal, Vol. VII., p. 131), and the third, or the type of the genus, 

 no more a plant than the other two, is an evident burrow. The "plant" 

 or fossil, according to the description, consists of a "round, flexuous stem, 

 with a spheroidal swelling at one end," the surface being covered with 

 "diagonal and longitudinal lines, as if made by the folding down of hair- 

 like filaments." It seems most probable that these lines represent the ar- 

 rangement of the mud particles thrown up during the making of the bur- 

 row. They are similar in appearance to the marks on T. venosum, but 

 hardly referable, as that is, to rill marks, on account of the curving and 

 twisting of the fossil. (Plate 9, figure 4). 



