Vol. 68.] 



IN THE ' PEKMIAN ' ROCKS OF HAMSTEAD. 



675 



the measurements does not give a very close analogy ; but this may 

 be due to the fact that, owing to the small size of the footprints — 

 length = 0*7 cm. — it has not been found possible to measure the 

 length of the toes with sufficient accuracy. 



The track of the tail of the animal, it may be mentioned, is 

 present in the Hamstead specimen. 



(4) Tracks of Animals other than Amphibia. 



The tracks described in the foregoing pages include all those 

 that cau, with more or less certaint}'^, be referred to those of 

 amphibia or reptilia. They include, however, by no means the 

 whole of the tracks shown on the surfaces of the sandstone beds, 

 or even the majority of them : for the largest proportion of tracks 

 present are of a different character, and have rather the appear- 

 ance of having been made by some kind of arthropod, probablj 



Fig. 29. — Tracks of Crustacea from Hamstead 

 (half of the natural size). 



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r 



a 



crustacean. The commonest of these tracks was evidently made 

 by a creature, each of whose feet ended in a claw or a sharp point. 

 Every successive footstep made a separate and isolated depression 

 in the soft muddy material, now represented by the marl-layers. 

 Each of these depressions became subsequently filled up with sand, 

 so that the tracks are now shown as casts on the under surfaces of 

 the alternating sandstone beds. There are two parallel rows of 

 these elevations in each separate track, one representing the 

 impressions of the right, the other the left feet of the animal. 

 Behind each cast of the claw-print of each foot is a depression on 

 the face of the sandstone which is doubtless the mould of the little 



