State Museum of Natural History. 



21 



Museum Building on Lodge street. The other slabs and frag- 

 ments which have all been preserved are temporarily placed 

 within the area fence at the southeast corner of the State Hall. 



I beg leave to recommend that some means be adopted for pro- 

 tecting these from the effects of the frost, and that every piece 

 shall be preserved until they can all be laid out in the same rela- 

 tion to each other that they occupied in the original rock. By 

 this means we shall be able to present a larger area of surface 

 marked by these tracks than has ever been shown before from any 

 source. This arrangement will also be important as enabling us 

 to learn much more of the habits of the animal making these 

 imprints, than can be learned from a single small slab, and more 

 than is now known of the characters and habits of the animal. I 

 would most earnestly recommend that this be done before any 

 specimens are permitted to leave the Museum collections on any 

 pretense whatever. 



In this connection it may not be inappropriate to give a brief 

 historical account of the discovery of tracks or foot-prints in the 

 Potsdam sandstone of this country. The occurrence of tracks or 

 trails upon the muddy or sandy beds of many of the geological 

 formations is already well known. These were made by animals 

 inhabiting the sea, or of others walking along the shallow water 

 near its margin, thus impressing the yielding sand or mud which 

 from receding tidal water or otherwise, may become hardened, 

 and also perhaps more commonly covered with a thin film of clay, 

 which prevents the intermingling of the succeeding deposit with 

 that below, and after the induration of the whole the separation 

 more readily occurs along this line of bedding. 



Until about forty years ago I am not aware that any tracks or 

 trails which were recognized as other than those of mollusks, had 

 ever been found below the horizon of the Clinton group. The 

 tracks in the New Red-sandstone of the Connecticut valley (orig- 

 inally referred to birds) are well known to every student of geology. 

 The tracks and trails, probably of crustaceans, in the Clinton 

 group have been known for nearly forty years, and some account 

 of them was published about thirty-six years ago, though 

 under an erroneous impression as to their nature. The first 

 information we have of foot-prints in the Potsdam sandstone 

 was derived from the Canada Geological survey, and the first pub- 

 lished account of these impressions was given by W. E. Logan, 



