BUEKOWS AND TKACKS OF INVEKTEBKATE ANIMALS, ETC. 595 



37. On Etjeeows and Tkacks of Inveetebrate Animals in Paleo- 

 zoic Rocks, and other Maekings. By Sir J. William Dawson, 

 LL.D.,P.R.S., P.G.S. (Eead May 14, 1890.) Pi^i^^ J)^.in2^^ 



Contents. 



Page 



§1. Introduction 595 



I II. Bilobites, Rusichnites, Arthrichnites, Protichnites, and Cli- 



mactichnites 595 



§111. Scolithus 602 



§IV. Sabellarites 605 



§ V, Trunk-like Concretions in the Potsdam Sandstone 609 



§ VI. Combinations of Worm-tracks with Eipple-marks and Shrink- 

 age-cracks 610 



§ YII. Branching Tracks 613 



I VIII. Eill-marks 614 



§IX. Conchiding Notes 617 



§ T. Inteoduction. 



The present paper is intended to contribute some recently acquired 

 facts to the solution of questions connected with these often proble- 

 matical markings ; and it will consist rather of short notes, illustrated 

 by photographs, than of a connected discussion of the subject. I 

 propose to notice the nature of certain markings sometimes referred 

 to plants, under the name of Bilohites, — to the true nature of the 

 Scolithus canadensis of the Potsdam Sandstone, — to certain tubes 

 similar to those of modern SahellcB, — to cylindrical concretions resem- 

 bling trunks of trees, — and to imitative markings, and peculiar trails 

 of doubtful origin. 



§ II. Bilobites, Eusichnites, Peotichnites, and Climactichnites. 

 (Figs. 1 to 6.) 



The name Bilohites, proposed by Dekay in 1823, was, as Kewberry 

 has shown,* originally applied not to objects of this kind, but to 

 casts of certain bivalve shells. It was therefore dropped in America ; 

 but it has been revived and has gained currency in Europe f, as 

 a term including various forms of markings referred to different 

 genera. The dominant characters are a band, or an oval mass, with 

 a median longitudinal furrow or ridge, and marked with transverse 

 or oblique furrows or striae, and with or without a marginal ridge. 



The writer was enabled to show in 1864 J that one of the most 

 remarkable of these impressions, Rusophycus grenvillensis of Bil- 

 lings, and Cruziana-\i\ie markings associated with it, were really 



* ' Science,' vol. v. no. 124, 1885, p. 508. 



t In Senhor J. F. N. Delgado's ' Etude sur les Bilobites et autres Fossiles des 

 Quartzites de la Base du Systeme Silurique du Portugal,' 4to, Lisbon, 1886, 

 and the ' Supplement,' 1888, numerous bibliographic references to other authors 

 treating of these and some allied fossils are given in full. 



I ' Canadian Naturalist,' n. s. vol. i. pp. 363, 458. 



