TRIAS OF THE UNITED STATES. 
381 
of the Trias, the remains of no less than eighty distinct 
species are described and figured. 
TRIAS OF THE UNITED STATES. 
New Eed Sandstone of the Valley of the Connecticut River. 
•—In a depression of the granitic or hypogene rocks in the 
States of Massachusetts and Connecticut strata of red sand¬ 
stone, shale, and conglomerate are found, occupying an area 
more than 150 miles in length from north to south, and about 
five to ten miles in breadth, the beds dipping to the east¬ 
ward at angles varying from 5 to 50 degrees. The extreme 
inclination of 50 degrees is rare, and only observed in the 
neighborhood of masses of trap which have been intruded 
into the red sandstone while it was forming, or before the 
Fig. 408. 
i w 
newer parts of the deposit had been com¬ 
pleted. Having examined this series of 
rocks in many places, I feel satisfied that 
they were formed in shallow water, and for 
the most part near the shore, and that some 
of the beds were from time to time raised 
above the level of the water, and laid dry, 
while a newer series, composed of similar 
sediment, was forming. 
According to Professor Hitchcock, the foot¬ 
prints of no less than thirty-two species of 
bipeds, and twelve of quadrupeds, have been 
already detected in these rocks. Thirty of 
these are believed to be those of birds, four 
of lizards, two of chelonians, and six of ba- 
trachians. The tracks have been found in 
more than twenty places, scattered through 
an extent of nearly 80; miles from north to 
south, and they are repeated through a suc¬ 
cession of beds attaining at some points a 
thickness of more than 1000 feet.* 
The bipedal impressions are, for the most 
part, trifid, and show the same number of 
joints as exist in the feet of living tridactyl- 
ous birds. Now, such birds have three pha¬ 
langeal bones for the inner toe, four for the 
middle, and five for the outer one (see Fig. Foot-prints of a bird, 
408); but the impression of the terminal i^™)Ft®iie^conne^^ 
joint is that of the nail only. The fossil ^^cut, 
foot-prints exhibit regularly, where the joints are seen, the 
same number; and we see in each continuous line of tracks 
* Hitchcock, Mem. of Amer. Acad., New Series, vol. iii., p. 129. 1848. 
