26 
PALAEONTOLOGY OF NEW-YORK. 
ICHNOPHYCUS. 
Among the numerous curious impressions and remains of plants and other bodies in the shaly 
sandstones of this group, these are interesting from their similarity in form to the Ornithicnites 
of the New Red Sandstone ; but since we have no evidence of the existence of such animals 
at this period, I have proposed a name significant of their form, and more for the purpose of 
attracting attention to the fact of their occurrence, than for the purpose of deciding their true 
relations, which cannot be done with the meagre materials we possess. 
415. 1. ICHNOPHYCUS TRIDACTYLUS (n.sp.). 
Pl. X. Fig. 7 a, b. 
Impressions tridactyle, apparently in series one before the other ; substance of the fossil 
resembling that of other species of marine plants. 
The only specimens seen are those represented on Plate X, fig. 7 a , b. The specimen 7 a 
represents the surface of a slab, with two tridactyle impressions arranged as in the figure. The 
impressions are indented, and the laminae depressed around them : the extremities are pointed, 
the central one being longest. They resemble very closely the tracks of birds in the sandstone 
of the Connecticut valley, but we have no evidence of the existence of birds at the period of 
the Clinton group. 
The specimen 7 b is in relief upon the under surface of a slab of shaly sandstone, and appears 
like a substance itself rather than a cast of an impression of this form. 
It will be observed that both the impressions on 7 a , and the one in relief 7 b, present an 
emargination behind, in which they differ from most of the Ornithicnites of the Connecticut 
river valley. 
Whatever these curious impressions may be proved to be, they are subjects of interest; and 
further investigation may throw light upon them, to enable us to decide their true relations. 
Position and locality. Blackstone’s quarries, associated with numerous species of marine 
plants. 
TRACKS OF GASTEROPODA, CRUSTACEA, OR OTHER MARINE ANIMALS. 
Among the evidences of the existence of organic beings, and of the condition of the ocean 
bed during the deposition of the strata composing this group, may be mentioned the occurrence 
of the tracks of various animals, some of which, as they passed over or just beneath the surface 
of the sand, have left a continuous furrow or trail, while others present the character of distinct 
and separate footprints. These trails, though not organic in themselves, are nevertheless so in¬ 
teresting that I present them in connexion with the other evidences of organic life at this period. 
From the character of the surfaces of the arenaceous beds in which they occur, I am inclined 
to the belief that many of them were made while the bed was exposed above water, and most 
