The vestiges of fishes are very numerous in the 
sandstone rocks of Connecticut River. We have not 
less than two dozen specimens from this locality; a 
number equal to all the other specimens in our collec- 
tion. ‘These impressions of fishes are generally from 
three to six inches long, and three or four imches 
wide. They are of the grand division denominated by 
Professor Agassiz “ heterocercal,” having their tails 
unequally bilobed, from the partial prolongation of 
the dorsal spine; and they are considered to be of 
lower antiquity than the fishes which are entirely he- 
terocercal. ‘The most remarkable of the fish-specimens 
in our collection is a CePHALAspPis (?): this fish is found 
in the specimen containing tracks of the Brontozoum 
Gracillimum, and traces of a turtle or tortoise. This 
fossil was discovered in the upper layer of the old red 
sandstone of Scotland, and had been mistaken by 
some for a trilobite: to us it appeared to be a Limu- 
lus, but further observation leads us to believe it to be 
a Cephalaspis. It exhibits a convex disc, four inches 
across, by two inches from above downwards, and a 
tail at right angles with the disc, the uncovered part 
of which is three inches long. The animal has been 
described by Professor Agassiz as being composed of a 
strong buckler, with a pointed horn at either termina- 
tion of the crescent, and an angular tail. 
