Vol. 68.] 



IN THE ' PEEMIAN ROCKS OF HA.MSTEAD. 



671 



In specimen D the fore foot is shown, but is so badly outlined as 

 to debar accurate measurement. On the same specimen is a series 

 of smaller footprints of the same tj^pe, referred to as Hsa, which 

 may be compared with IcJmium gam2)Sodactylum (minus). 



The Middle Coal Measures of Kansas have furnished us with a 

 footprint similar to, but not identical with, the Hamstead specimens 

 of this type. It is described and figured by Marsh as Dromopv.s agilis. 

 In both the Hamstead and American forms there are five slender 

 curved and clawed toes indicated on the impression left by the 

 hind foot, and four usually on the fore foot ; the first toe spreads 

 very much from the line of track, ;ind the hind foot somewhat 

 oversteps the fore foot. The principal points of difference between 

 the two forms are : (a) the claws of Dromojnis agilis appear to 

 have been the longer and sharper ; (b) the hijider part of the 

 foot is not impressed in H., but is clearly outlined in the other ; 



Fig. 24. — TL.from Hamstead Fig. 2h. — Ichnium gampso- 

 ( natural size). dactylum from Alben- 



dorf (tiuo-thirds of the 

 natural size). 



(c) the general appearance of the footprint and the straighter 

 aud more distinctly impressed toe-prints in the American specimen 

 suggest that the animal making these impressions was stronger 

 and heavier than the one forming footprints of the type Hj. 

 Dr. G. Hickling figures a similar footprint from the Permian 

 sandstone in the neighbourhood of Penrith : it is a single small 

 footprint with five slender and curved toes, and appears to agree 

 exactly with the footprints of Type Hg (fig. 24) and with Ichnium 

 gampsodactylum (fig. 2b). Footprints of animals probably identical 



