264 THE OLDEST AIR-BREATHERS 



ground in a plantigrade manner. These have also the outer 

 toe separated from the others, and sometimes provided with 

 a long claw. The fore foot is sometimes smaller than the 

 hind foot, and differently formed. 1 In these respects they 

 resemble the great Labyrinthodont Batrachians of the sub- 

 sequent Trias. Their stride also is comparatively short, and 

 the rows of impressions wide apart, as if the body of the 

 animal had been broad, and its limbs short. 



We have thus two types of quadrupedal footprints, to the 

 first of which I have given the name Hylopus, and have 

 restricted the term Sauropus, 2 to the second. The first 

 apparently belongs to the usually small reptiles of the group 

 Microsauria, which had a well-marked lizard-like form, with 

 well-developed limbs, and perhaps also to some of the smaller 

 Labyrinthodonts, the second to the group of Labyrinthodontia, 

 which were often of large size and with stout and short limbs 

 and plantigrade hind feet. There are also some small and 

 uncertain tracks, which may have been made by newt-like 

 animals with short feet, and a singular trail of large size, and 

 with a row of impressions at each side (Diplichnites), 3 which, 

 if made by a vertebrate animal, would seem to indicate that 

 serpentiform shape which we know belonged to some Carbo- 

 niferous Batrachians. 



The bones of these animals, however, hitherto found in 

 Nova Scotia, may all have belonged to the two groups first 

 named, the Labyrinthodontia and Microsauria, and I shall 

 proceed to give some examples of each of these. 



In leaving the footprints, I may merely mention that the 

 animals which produced them may, in certain circumstances, 

 have left distinct impressions only of three or four toes, 



1 Fine slabs of these footprints have been presented by Mr. Sandford 

 Fleming to the Geological Survey of Canada. 



2 Given by King. 



3 Impressions and Footprints of Animals, Am. Jour. Set., 1873. 



