OF CENTRAL CANADA PART IV. 



213 



is that of a long ribbon, five or six inches wide and several feet in 

 length, mostly with a kind of beaded border and central groove, and 



FIG. us. 



Arthrophycus Harlani (Hall). 

 Medina and Clinton Formations. 



FIG. 114. 



Rusophycus bilobatus (Hall). 

 Medina and Clinton Formns. 



FIG. 115. 



Fucoides (=SpirophytonJ cauda-galli. 

 Portage-Chemung Formation. 



FIG. 116. 



Climactichnites Wilsoni (Logan). 

 Potsdam Formation. 



with numerous transverse furrows. Protichnites consists of a central 

 groove, more or less interrupted, with on each side, at nearly regular 



FIG. 117. 



distances apart, a series of small pits or indentations, varying in 

 number in different impressions, or being occasionally absent.* 



* The central groove, by those who consider these impressions to be crustacean tracks, is 

 supposed to have been made by the caudal spine of the creature, and the lateral pit marks by 

 its claws. But these pit marks differ in number in different impressions, and as the number 

 of the feet in the Crustacea is a very important and constant character, Professor Owen has 



