﻿Fucoids of the Cincinnati Group. 



153 



The burrows of the beetles are generally longer than those of the larvae, 

 and are made in a different way. Instead of the transverse lines noticed in 

 the larvae burrows, the mud seems to be thrown up in a series of pellets, 

 arranged in lines sloping backward from the center, and thus giving quite 

 a different appearance (Plate 8, figures 2a and 2b). Uncovered, as in the 

 case of larvae burrows, they also assume a very different aspect. 



It has been noticed in a basin of muddy water that, on the settlement of 

 the sediment to the bottom, it is often arranged in curious, irregular shapes 

 by the small inhabitants of the water (Plate 9, figure 3). It would seem 

 that these animals make their burrows by gathering the small particles of 

 mud together and cementing them in some way that allows considerable 

 stretching before breaking up. These burrows begin and end abruptly, 

 and follow no regular pattern or design in the arrangement of the mud par- 

 ticles. 



FOSSIL TRAILS AND BURROWS. 



Having now noticed some of the markings on modern banks, it will be 

 found that on ancient coast lines similar ones were made. Professor Hall 

 in the Palceontology of New York (Vol. II.), gives a number of plates 

 showing the markings to be noticed on the rocks of Clinton and other 

 formations. He recognizes that some of these are animal burrows and 

 some trails; but he has, at the same time, erroneously identified as plants 

 certain other markings which were found in rocks of lower formations. It 

 is to errors like these — not alone of Professor Hall, but of others who have 

 followed him — that attention will now be directed. It is likewise the in- 

 tention to confine the present notice to such of these markings as are found 

 or have been described as plants from the rocks of the Cincinnati group. It 

 has already been intimated that there can be little objection to the naming 

 and describing of burrows and trails, or Ichtholites, as long as they are re- 

 garded in their true light; but it certainly is neither logical nor scientific 

 to speak of and refer to them as Algae, when they have no connection 

 whatever with the class. Taking the genera up separately, and examining 

 each, will be the best way of showing the errors which have arisen from a 

 misconception of the true character of these fossils. 



Genus Rusophyctts, Hall. 1842. 



The genus Rusophycus was described by Professor James Hall in Vol. 

 II. of the Palaeontology of New York, page 23. He considered the fossils 

 referred to the new genus to be plants or parts of plants. He gave as the 

 generic character, " Plants consisting of simple or branched stems, which 

 are transversely rugose or wrinkled." The genus was, at the same time, 



