252 an attempt to describe the animals that made 



Explanation of the Plates. 



N. B. — The tracks only of the species enumerated are represented. 



Plate I. Fig. 1. Brontozoum giganteum. 



II, " 1, 2. B. loxonyx. 



" 3. B. gracillimum. 



III. " 1. B. expansum. 



«' 2. B. Sillimanium. 



IV. 



V. 



VI. 



VII. 



VIII. 



