CONNECTICUT RIVER SANDSTONE. 43 



shows so well the impression made by the integument of the skin upon the plastic surface 

 of the soil. 



The species, like that of Plate 14, is the Brontozoum minusculum of Hitchcock. 



PLATE XVII. 



A photograph of the same species as the last, from a specimen at Amherst, but more 

 reduced, taken to show the impression of the integument of the skin. 



PLATE XVIII. 



A fine footprint, nowhere particularly described by Dr. Deane, and which appears 

 different from any figured by Dr. Hitchcock in his Ichnology, unless, indeed, it be that of 

 a hind foot of his species the Plesiornis quadrupes. A beautiful specimen of this 

 form and character may be seen in the cabinet at Yale College. 



PLATE XIX. 



No description by Dr. Deane. The original of this is in possession of Mr. Roswell 

 Field, and the drawings are from two of seven consecutive tracks. These impressions 

 are probably those of the animal described by Dr. Hitchcock under the name of Apat- 

 ichnus circumagens. See Plate 34 and description, for an account of this species. 



PLATE XX. 



The several impressions upon this plate are doubtless the footprints of birds, 

 yet they do not sustain an intimate comparison with the other ornithoid footprints 

 illustrated in this paper. The resemblance consists merely in the tridactylous 

 character of the feet. They represent a large proportion of the ornithoid foot- 

 prints that do not present the articular division of the toes. This class of footr 

 prints offers a great variety of modified forms. They are sometimes distinguish- 

 able by slender lines merely, and sometimes they are much bent or distorted. 

 They are not actual impressions of the foot, but are changed by having been 

 made upon material which was too soft to retain the genuine impress of the 

 plantar surface of the foot. When the foot is withdrawn after penetrating the 



