CONNECTICUT RIVER SANDSTONE. 25 



movement for the walking. The smaller, or anterior footprints, are arranged in 

 pairs (PL 32), at the right of the Plate, and are so perfectly defined as to exhibit 

 the phalangeal divisions of the toe. The posterior or ornithic feet will readily 

 be recognized; but in addition to those of the preceding examples (Pis. 33 and 

 34), the tarsus is prolonged backward, *so as to present its entire and unblemished 

 impress. The entire group of impressions was produced by the animal when in 

 a sitting posture ; but, excepting distinctions depending upon a difference of species, 

 they appear to be essentially identical with those of Plates 33 and 34, one set 

 being impressed in the act of walking and the other in leaping. The singular 

 resemblance of the posterior feet in these remarkable forms of the quadrupedal 

 footprints to those of the ornithic varieties, is a circumstance of significant meaning. 

 Associated as they are with footprints of unquestionable reptilian type, the first 

 fact appears that throws a doubt upon the subject of the ornithic origin of the 

 footprints. If it shall be proved by future discoveries that the animals making 

 these complicated impressions possessed the additional power of walking upon 

 their posterior feet alone, the ornithic theory of the footprints would be settled 

 in a summary manner, impregnable as it now seems to be. 



Another modification of the ornithic-reptilian footprints appears upon Plate 35. 

 It might appear, by the wide separation of the right and left sets of feet, and 

 from the dragging of the toes in all the feet from step to step, that the animal 

 was created upon some testudinal type, but the character of the posterior foot 

 forbids this inference ; and, moreover, there is no evidence that tortoises existed 

 during the deposition of the sandstone formation, although a different opinion 

 has been formerly held. 



The footprints upon Plates 30, 37, 38, and 39 are those of bipedal reptiles, 

 and their origin is involved in profound obscurity ; those upon Plate 30 are 

 remarkable for the form of the feet, and for being associated with the impression 

 of a dragging tail; those upon Plates 38 and 39 are distinguished for their 

 diminutive size, while that upon Plate 37 is distinguished for its enormous magni- 

 tude. It is the largest, the most massive and solid, footprint ever discovered, 

 the original being seventeen inches in length and eleven in breadth. These 

 stupendous but graphic impressions cannot be contemplated without astonishment; 

 but it is vain to assign the creature who made them a place in the scale of 

 animal organization. 



It will now be understood, that the footprints indicate by their analogies ani- 



4 



