Vol. 68.] IN THE 'peemian' eocks of hamstead. 663 



Thenaropus lieterodactylus King^ was found in the Coal Measures 

 of Pennsylvania. Especially in the spacing of the feet in the 

 tracks this form is like thai of the Hamstead type H^. The 

 shape of the footprint, however, serves to separate this American 

 species from the British form. Purther, the toe-impressions in 

 the former are much longer proportionately. The first toe is also 

 more distinctly marked and longer. 



From the British rocks of the Lower Permian — Penrith Sand- 

 stone — near Penrith were obtained the footprints modelled by 

 G. Varty Smith. The description of the footprint noted by him 

 as Cast 1 agrees with our description of the Hamstead form H^. 

 No figure of the Penrith footprint or of the cast is, however, given 

 in Mr. Smith's paper." 



Sub-Type Hi^. Ichniotheejum cott^ Pohlig. (See also p. 660.) 



Specimens precisely similar in character to that of Hia are 

 recorded in Prof. Pabst's memoir from the Rothliegende (Upper and 

 Middle) of Thuringia, and from the Pothliegende of Silesia, Bohemia, 

 and Moravia. The Hamstead specimen (fig. 13, p. 662) seems 

 to me to be an imperfectly-impressed footprint of type H^. The 

 Continental analogue of Hia is termed Ichniotherium eottce (fig. 14). 

 No footprints at all like Hi^ are known from other Permian strata 

 or from Carboniferous rocks. 



Sub-Type H^. Ichnifm sph^eodactylum (minimum) Pabst = 

 Icliniotlierium eottce (minus) Pohlig. (See also p. 660.) 



Sub-Type H^ I consider to be the same as Pabst's Ichnium 

 spJicerodactylum (minimum), which occurs in the Middle and Upper 

 Pothliegende of Thuringia. Both Hi^ and /. splioerodactylum 

 (minimum) are footprints with a broad ball. The width of the 

 foot exceeds the length. There are five short toes with conspicu- 

 ously semispherical endings, without any mark of a claw. The 

 measurements of Hi also agree in general with those of its German 

 analogue (see p. 660) ; but the toe-prints in the Hamstead speci- 

 mens are considerably the shorter, possibly due to a greater hard- 

 ness of the ground at the time when the impressions were made. 

 That this supposition is the correct one is rendered more probable 

 by the rarer occurrence in the prints of H15 of the first toe, which 

 naturally bore least of the weight of the animal. 



Type H2. IcHNiU3i pachtdacttltjm Pabst. Mne specimens in 

 relief. (See figs. 15 & 16, p. mb.) 



The footprints included here show a broad ball. There were 

 five toes, although frequently only three or four are visible. These 

 toes are thick, and their ends are obtusely rounded. The fourth 



^ A. T. King, ' Description of Fossil Footmarks found in the Of.rboniferous 

 Series in Westmoreland County, Pennsylvania' Amer. Journ. Soi. vol. xlviii 

 (1845) pp. 343-52 & vol. xlix (1845) p. 21{1 



- G. Varty Smith, ' On furtlier Discoveries of the Footprints of Vertebrate 

 Animals in the Lower New Eed Sandstone of Penrith' Q. J. G. S. vol. xl 

 (1884) p. 479. 



