INo. 2.] DAWSON — IMPRESSIONS AND FOOTPRINTS. 69 



been produced by a large crustacean or by a gigantic worm, or 

 by a serpentiform batrachian. I have since found a very perfect 

 but smaller series on a sandstone of the Upper Coal-formation 

 near Toney river, which in the varying distances of the impres- 

 sions seems to show that they were made by prominent movable 

 j)oints, while the absence of any mark or smoothing between the 

 rows shows that the body of the animal was borne above the 

 sand. I have hence been induced to suppose that these imprints 

 may have been produced by the pectoral or ventral fins of fishes 

 armed with strong spines, on which the creatures may have exe- 

 'Cuted a sort of walkins: movement when in shallow water. In 

 my collection from the Joggins there is a spine which I have 

 figured and described in my Acadian Geology under the name 

 Gyracanthus diqylicatus, which if we can suppose it to have been 

 •a pectoral or ventral spine, would produce precisely such 

 impressions as those of the smaller series above mentioned. 

 The impressions of the type of DipJichnites are known to me 

 •only in the Carboniferous. Scerlclinites of Billings, from the 

 Anticosti group,* has some points of resemblance to it, but is 

 •essentially distinct. My species may be named D. cenigma. 



Rahdichnites, Dawson. 



Under this name I would designate the straight or slightly 

 •curved marks usually striated or grooved longitudinally, and 

 •either single or in pairs, which abound on some Carboniferous 

 beds, and also in much older formations. At Horton Blufi", in 

 beds holding remains of fishes, numerous footprints of crus- 

 taceans and reptiles, and scratches which were probably made by 

 the fins of fishes, these marks abound. They were evidently 

 furrows drawn by pointed objects trailed over the mud, and 

 reproduced in relief on the under surfaces of the beds next 

 deposited. Some have been produced by rounded points and 

 are semi cylindrical. Others are the work of chisel-shaped, 

 pointed, notched or fimbriated organs, giving a variety of more 

 •or less close subordinate grooves or striae. In some cases they 

 pass into or are associated with punctures or impressions made 

 perpendicularly like those last noticed, and this is especially the 

 >t2ase with some of the smaller varieties. The whole of these 



* Report on Silurian Fossils of Anticosti, 1866, 



