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Cincinnati Society of Natural History. 



that they are trails, or impressions of trails, of some sort of articulates, may 

 be considered as probable. But what sort of articulates, is problematical. 

 From the evidence now at hand, it seems likely that they are casts of trails 

 of trilobites, or else casts of their bodies. Since the discovery of the loco- 

 motory appendages of the trilobite in the Oxford specimen,* a better idea 

 can be formed of how the trail would look than it could before. Obscure 

 specimens, undeterminable in themselves, become explainable when viewed 

 through more perfect specimens. A fossil in the collection of this Society, 

 long referred to the fucoids, is now recognized as a cast of the remains of 

 the locomotory appendages of an Asaphus, such as was found at Oxford. 

 Similar features in other specimens seem to show an approach to such re- 

 mains. Some of these other specimens are very like species of Cruziana. 

 Especially is it so with C. Carleyi, n. sp., though in this the heavy lobes 

 on each side seem to militate against its having its origin there. Still, all 

 analogies seem to point to some of the forms referred to Cruziana as the 

 remains either of trilobites or else their trails. If the first, they still re- 

 tain the shape, though they have lost all the outside shell. 



Cruziana (Rusophycus) subangulata and C. clavatum, are two 



species described by Hall in Paleontology of New York, Vol. II. One 

 is evidently synonymous with the other, the differences being merely in 

 length. The first is longer and more regular than the last, but this con- 

 stitutes the main difference. Neither one is a fucoid. Both are trails of 

 Grasteropods, similar to those produced at present by Melania. The de- 

 pressed line along the centre, with the corresponding elevated margins, are 

 just what would be produced by the passage of the foot of a Gasteropod 

 over soft mud. The first (subangulata), has not before been recorded 

 from this vicinity, but last spring a rock was found at Ludlow, Kentucky, 

 containing undoubted specimens of it. 



Cruziana (R.) aspera, S. A.M., is neither a fucoid nor a track. It is a bur- 

 row, made by some one of the numerous annelids which lived on the Silurian 

 sea-beaches, and which have left only their jaws in the rocks to tell the 

 tale of their having lived. This species is rough on the upper surface with 

 numerous papillae, these having no doubt been caused by the mud or sand 

 thrown up in the course of the making of the burrow. (Plate 8, figure 

 3). There is no sign of branching, but the burrows often cross each other 

 at various angles. There is a slight depression down the centre, and the 

 sides are elevated above the level of the rock, as would naturally be. the 

 case with a burrow made just beneath the surface. 



*See this Journal, Vol. VI., p. 200. 



