IT. DESCRIPTION OF TRACKS FBOM THE FINE-GRAINED SILICEOUS 



MUDSTONES OF THE KNOYDART FORMATION (EO-DEVONIAN) 



OF AKTIGONISH COUNTY, XOVA ScoTiA. 1 BY H. M. AMI, 

 M. A., D. Sc., F. G. S., of the Geological Survey of 

 Canada. 



(Read May ISth, 1901.) 



ICHTHYOIDICHNITES ACADIENSIS, n. sp. 

 Plate no. 2. 



1897, Protichnites carbonarius, Fletcher, (partim) Annual Report, Geol. Survey 

 of Canada, new series Vol. 2, p. 68 P. 



These tracks are arranged in pairs and indicate an animal 

 possessing bilateral symmetry with powers of locomotion and 

 suspension in water without leaving a trail or mark of the body 

 proper. They were evidently made by some fin or spine-like 

 appendage attached to the body of the organism, which may 

 have been that of an acanthodian or other early form of fish 

 existing in the early Devonian lake, sea or estuaries of Nova 

 Scotia. 



There are eight pairs of tracks preserved on one slab showing 

 seven completed strides, steps or series of advances. They con- 

 sist of two more or less parallel linear depressions, which spread 

 slightly anteriorly in the direction of progress or advance for- 

 ward, accompanied posteriorly by two somewhat raised ridges 

 or monticules, the result of the accumulation of the once soft 

 fine mud or sediment by the fine or spine-like pointed appendage 

 in the forward motion of advance. As preserved, the eight 

 pairs of tracks indicate that at the time they were made the 

 animal took a turn to the left and changed the direction of its 

 course by an angle of thirty-eight degrees. 



1 Published with the permission of the Director of the Geol. Survey of Canada. 



(330) 



