DESCRIPTION OF DEVONIAN TRACKS, ETC. AMI. 



331 



The impression or track made by the left fin or spine appears 

 slightly in advance of that made \)y the right appendage in all 

 the eight pairs preserved on the type specimen, which seems to 

 indicate that the creature used its appendages in locomotion in 

 -a slightly alternating manner, striking the mud with the left 

 appendage first. The average distance in advance of the left 

 imprint or track from the right is between three and four milli- 

 metres measured in a direction at right angles to the course 

 taken by the organism from the apices of the monticules. 



The slabs on which these tracks are preserved consists of a 

 thin-bedded, fine-grained, greenish and chocolate-red coloured, 

 siliceous sandstone with numerous minute glistening scales and 

 pai tides of mica along the divisional planes of stratification. 



The following table is prepared with a view of giving the 

 number of pairs of tracks preserved on the type-specimen, the 

 exact measurements of the linear depressions or imprints made 

 by the spine-like appendages as well as the distances between 

 them, the relative size and distance between each and the 

 different pairs of the monticules measured from their apices, 

 together with the length of the stride : 



MEASUREMENTS IN MILLIMETRES TAKKX FROM TYPE-SPECIMEN. 



