378 



exhibited, the anterior portion was much worn ; the roots, 

 also, were very much developed, which is never the case, 

 except when the tooth is old. As the tooth is worn away 

 in front, the socket becomes absorbed in front of the tooth, 

 the tooth advances, and the socket is built up behind it. 

 In this way the tooth actually moves forward, and, in the 

 same manner as the human tooth, is forced upwards or 

 downwards, only one moves in a vertical, the other in a hori- 

 zontal direction. 



President Hitchcock having been invited to address the 

 Society, gave some of the results of his examinations in the 

 Connecticut Valley, in reference to fossil foot-marks. 



He stated that he had very recently measured a section across 

 the valley of the Connecticut, where are several localities of fossil 

 foot-prints. This section (which he illustrated by a map) extended 

 from the hypozoic rocks on the east, to the mica slate on the 

 west ; the gneiss of the east forming the high hills. The dis- 

 tance across is eight miles. The gneiss dips about 30^. The 

 sandstone on the west side of the Connecticut river, in Gill, dips 

 irregularly, having remarkable curves, but soon assumes the 

 normal or easterly dip. From the results of his observations, he 

 believed the perpendicular thickness of the sandstone in this 

 valley, throughout this width of eight miles, to be over fourteen 

 thousand feet. 



The localities of the foot-marks are various. One is near the 

 east end of the section ; and at the place called the Horse Race, 

 are localities on both sides of the river. Half a mile farther 

 down the river, near E.oswell Fields, is the locality whence was 

 obtained the largest and best slab of fossil foot-prints ever found, 

 or, as he was (to use his own words) " bold enough to say, ever 

 would be found," and which is now the property of this Society. 

 Smaller specimens of foot-marks occur at the ferry at Turner's 

 Falls, and also a hundred rods below the falls, on the north bank 

 of the river. From the results of his examinations, he had come 

 to the conclusion that the thickness of the rock above these last 

 named foot-prints, is four thousand feet. The most abundant 



