310 Mr. S. M. Saxby on the Discovery of Footmarks 



hydrous acetic acid. According to that hypothesis, the mea- 

 sure of the test atom of this acid in solution should be equal 

 to that of 3 atoms of water =48*21 septems (= 16*07 x 3), 

 whereas the measure actually varies in different solutions 

 from 86*06 septems to 63*31 septems. It follows, that 

 Dalton's hypothesis can never be used in the analytical ex- 

 amination of organic substances of unknown composition. 

 [To be continued.] 



XLVII. On the Discovery of Footmarks in the Greensand of 

 the Isle of Wight. By S. M. Saxby*. 



TNDER the impression that footmarks of extinct animals 

 ^ have not before been found in any part of the world at 

 a higher stratum level than that of the new red sandstone, I 

 think it may be interesting to communicate to your readers, 

 that some time since, while examining the fallen blocks of crag 

 and freestone on the shore at Ventnor, I discovered distinct 

 impressions of the feet of animals of various kinds, strongly 

 indented in the flinty blue rag which forms the bed of the free- 

 stone. With the exception of the marks left by the crusta- 

 ceans on the oolite near Bath, I am not aware that within the 

 range of 3000 feet (which may be the average depth between 

 the freestone and the new red sandstone) any traces of animal 

 footmarks have been found. After thoroughly searching the 

 locality, I found and removed to my residence the blocks de- 

 scribed as under. 



Block 1 bears a good and interesting impression of the feet 

 of a three-toed creature, very similar in its general character 

 to the Ornithichnites giganteus, as figured by Dr. Buckland in 

 the Bridgewater Treatise, plate 26 b ; differ- 

 ing however in the angles subtended by 

 the toes, which in the above plate measure 

 about 33°, while in this the angle exceeds 

 50°; and the mark of a joint in the mid- 

 dle toe in this specimen is much more 

 strongly given ; and indeed the impression 

 altogether cannot be mistaken for an acci- 

 dental resemblance to the foot-print of an 

 animal. On the same block there are other 

 marks, which, although evidently those of 

 animals, are not such as I will venture to describe. The 

 length of the above three-toed impression is about 7 inches. 

 There is some indication of a hind-toe. 



* Communicated by the Author. 



