Prof. Hitchcock on IchnoUfhology, or Fossil Footmarks. 307 



leads me to remark, that I fear the terms Ornithoidichnites and 

 Sauroidichnites convey an impression of a wider distinction than 

 exists between these two subdivisions. For in fact they pass in- 

 sensibly into each other, and, with a few exceptions, all probably 

 were made by the same tribe of animals. 



The next new species I have to propose, is a very distinct, 

 though very anomalous one. I call it a Sauroidichnites, because 

 it has somewhat the aspect of the foot of a Saurian ; and yet it 

 has but three toes, whereas a Saurian has always four, and gene- 

 rally five. 



Sauroidichtiiies abnormis. Toes three, all directed forward : 

 the lateral ones diverging about 30°, and connected by a base two 

 inches long, the base and the inner toe appearing like a single 

 bent toe : middle toe with a deep impression along its anterior 

 part, but scarcely distinguishable on its posterior part. Heel 

 extending backwards nearly an inch, on a line with the outer 

 toe. Length of the middle toe, nearly three inches ; of the foot, 

 four inches ; and of the step, eighteen inches. Fig. 6 shows the 

 right foot, and fig. 7 the left foot. 



This remarkable track was found by Dr. Deane at the same 

 place as the specimens already referred to, viz. a little above Tur- 

 ner's Falls in Gill. It is very distinctly impressed upon a gray, 

 perfectly smooth, micaceous sandstone; and fortunately there are 

 several tracks showing the right and left foot most distinctly. 

 At first, I thought it was probably a perfect example of the Sau- 

 roidichnites tenuissimus, described in my Final Report, of which 

 I possess only imperfect specimens. But it is impossible to make 

 them out identical. 



Anomalous as is this track, there is a fact still more anomalous, 

 in the very distinct specimens before me. In two instances, and 

 these are all that I possess, while the middle toe of the left foot 

 lies in the direction in which the animal moved, that of the right 

 foot is turned nearly 45° towards the left hand, as is shown on fig. 

 ' 8, which was copied by a pentagraph from the specimens. Had 

 this singular inflection existed in both feet, I should have sup- 

 posed it a law of the species. But nature is not so partial as to 

 bestow a peculiarity upon one organ, and withhold it from the 

 twin organ. And I suspect that the animal's right foot might 

 have been injured, so as to give it an inflected position ! 



