114 EOYAL SOCIETY OF CANADA 



prints are not naturally placed in this scheme can suggest improvements. 



The reference to the supposed print of the tail given in the 

 margin will suggest a different arrangement to those who think this 

 character has sufficient regularity and permanence to be of value as 

 a primary means of classif}'ing the impressions. 



Taking the form of the footmark and the number of the prints 

 left by the digits as a primary basis for classification, one may make 

 the following remarks on the groups indicated. 



Group 1 is distinguished by having five slender toes on each foot. 

 Notolacerta Missouriensis of E. Butts ('91)— PL IIT., figs. 1 and la. — 

 may be taken as the type of this group. 



Dawson's name Hylopus has been retained for the 2nd Group — 

 PI. I., figs. 3 and 4. It contains two species described by Sir "William 

 Dawson from the Lower Carboniferous beds of Nova Scotia, as he 

 asserts they have five toes on each foot. ( ?) The species are Hylopus 

 Hardingi and H. Logani. H. caudifer is placed here as it is included 

 in Hylopus by Sir William, but his figure gives only four toes and 

 shows a good sized sole. This group needs further elaboration. 



Group 3 is established to contain a remarkable type of footmark 

 distinguished by the possession of long claws on both feet and by having 

 a heavy heel mark, the paws, therefore, had great grasping power, such 

 as was possessed by the sloths. A fuller description of this type will be 

 given in a future communication to the society — PL III., fig. 4. 



At Group 4, we pass from the tracks presenting impressions of five 

 toes on both feet to the much larger division, in which, while the hind 

 foot shows the print of five toes, the fore foot has only four. Here fall 

 most of the footprints of the Palaeozoic that have been described, and 

 they are classified in this scheme according to the form and heaviness 

 of the toe and heel marks. 



Group 4 may be represented by Marsh's Dromopus agilis — PL II., 

 figs. 3 and 3a — from the coal measures of Missouri, wbich possesses 

 long slender toes. To it may be referred Notolacerta missouriensis, 

 Butts. 



Group 5, Batrachichnus plainvillensis of Woodworth, and a new 

 species from the Joggins, Dromopus celer. The footprints of these 

 two are very much alike, in form and size, but one shows a strong tail 

 impression and the other none. 



Under the name Thenaropus, King described several species of 

 footprints which he afterward transferred to the genus Sphasropezium. 

 He in the first instance described Tlicnaropus heterodactylis mthout 

 a name in connection with the species of Sphaeoropezium subsequently 

 transferred. In the second communication (some months later, tO' the 

 Am. Jour. Sci.), he requested that the name Thenaropus should be 



