596 SIR J. W. DAWS0I7 ON BURROWS AND TRACKS OP 



burrows and tracks of marine animals, probably Crustaceans. He 

 arrived at this conclusion by a careful study of the impressions made 

 by the recent Limulus polyphemus on muddy and sandy bottoms, 

 and by the application of these results to the explanation of a very 

 fine exposure of the impressions above-named in the works under- 

 taken for the enlargement of the Grenville Canal, on the Ottawa 

 Eiver. In this paper, descriptive of the facts observed at Grenville, 

 it was proposed to substitute the generic name Miisichnites for lluso- 

 phycus or Rysopliycus, and it was pointed out that the so-called 

 fucoids of the genus Arthrojpliycus were probably of like nature, and 

 might be placed in the same category with the impressions described 

 by Logan as Climacticlmites from the Potsdam -Sandstone *. These 

 observations were supposed to have conclusively settled the question 

 as to the nature of all the Bilohites ; but little attention seems 

 to have been given to them by European Palason tologists. Nathorst 

 has, however, arrived at similar results, in a somewhat similar 

 manner, by comparison with modern impressions f ; and Williamson 

 has described as casts of animal-tracks markings of this nature 

 from the Yoredale rocks J. Bureau has also adduced some striking 

 evidences in favour of the theory that some at least of the Bilohites 

 are the work of Phyllopod Crustaceans §. Saporta, Delgado, and 

 others still regard the Bilohites as true Algae, and Schimper 

 describes one form as a plant, under the name CrossocJiorda. In 

 so far as American examples are concerned, it may be considered 

 as settled that they may best be explained in the way above in- 

 dicated. The following genera may be included in this general 

 statement : — 



Eusichnites = Rusophycus, JIall. 



Arthrichnites = Arthrophycus, Harlan. 



Cruziana, UOrhigny. 



Climactichnites, Logan. 



Preena, liouault. 



Crossochorda, Schimper (in part). 



These impressions pass into Proticlinites of Owen through such 

 forms as P. Davisi of Williamson ||, and the Scerichnites of Billings^ff 

 and DiplicJinites of the author**. They are connected with the 

 undoubted worm-tracks of the genus Nereites by specimens of 

 ArtJiricJinites, of w^hich I have several in my collection, and in 



* Canacl. Nat. Geol. vol. v. p. 279. 



t Kongl. Svenska Vetenskaps-Akad. Handlingar, vol. xviii. No. 7, 1881 ; eleven 

 plates, 104 pages, including an Abridgment in French. The List of Books and 

 Memoirs treating of Trails and Tracks, from 1823 to 1881, occupies six of the 

 quarto pages in this work. Also ' Nouvelles Observations sur les Traces des 

 Animaux;' Stockholm, 1886. 



J Mem. Manchester Lit. & Phil. Soc. 3rd series, vol. x. 1885, pp. 19-29, 

 3 plates. 



§ Comptes-rendus, vol. 104, 14 Fevrier et 4 Juillet, 1887, page 7 of the 

 author's reprint. 



I Op. cit. pi. i. fig. 4. 1[ Catal. Sil. Foss. Anticosti, 1866, p. 73. 



** Amer. Journ. Sci. ser. 3, vol. v. 1873, p. 19, and p. 23, fig. 3. 



