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POPULAR SCIENCE REVIEW. 
radiating like a fan ; and those attached to a long tail of twenty vertebrae 
radiating laterally so as to form a leaf-like shape broadest at the terminal 
end. The head and neck are unknown. The feet, like those of birds, con- 
sist of a strong tarsus of one bone, trifid at its lower end for the attachment 
of three toes, which terminate in strongly hooked claws. But, unlike a bird, 
the joints of the lower part of the back, instead of being united into a large 
bone called the sacrum, all remain separate ; and the pelvic bones, into 
sockets in which the thigh-bones work, instead of being large and extending 
along the sacrum as in birds, are small, and like those of the Pterodactyle. 
A further peculiarity is the length of the tail, which contains twice as many 
vertebrae as that of a bird, and, what is more important, gradually tapers to 
the end instead of terminating in a bone larger than the others. Until more 
is known of it, and its structure has been carefully compared with that of 
other animals, nothing but a guess can be given as to whether it is bird or 
reptile ; Von Meyer seemingly inclines to the former view, and names the 
genus Archfeopteryx ; Dr. Wagner, however, thinking it a reptile, gave it 
the name of Griphosaurus. Should the latter supposition prove correct, it 
will furnish one more illustration of the fallacy of Cuvier’s doctrine that an 
unknown creature can be restored from a single bone ; for, had the tarsus 
only been found, it would as surely have been referred to a bird, as the 
similar bones from the upper greensand of England. 
At a late meeting of the Geological Society, Sir W. Logan exhibited a 
plaster cast of some remarkable impressions found at the base of the 
Cambro-Silurian rocks, in the Potsdam Sandstone of Canada. These 
markings, certainly the trails of some animal, are about six inches wide, with 
the sides parallel and elevated like a tramway, and extend uniformly over 
the slab for several yards, sometimes straight and sometimes curved ; oidy a 
central ridge appears wherever there is a bend. But what is most singular 
is, that at distances of about two inches there are transverse ridges, the 
spaces between which are inclined planes deepest in the direction from which 
the creature was going ; so that the trails resemble more than anything a 
narrow Venetian blind when shut. Nothing whatever is known of the 
animal except the story told by its tracks. The cross-bar ridges show that it 
did not move smoothly and uninterruptedly like the hedgesnail and most 
other molluscs, but with a uniform jerking motion, which suggests the proba- 
bility of its being a crustacean. The tramway-like ridges which are due to 
the weight of the body drawn over the sand indicate an animal without hind 
limbs to support the tail. The inclined depressions behind the cross ridges 
will suggest that motion was made chiefly by a pair of limbs about the head 
which were used together, so that by elevating the front part of the rather 
rigid body the tail was pressed into the sand, when the creature would draw 
itself along rapidly till its whole length rested on the sand again, just as 
would a child, trying to move similarly ; hence the tail would be drawn out 
of the depression it first made, then impressed again, and so on. Judging 
from the short distance between the cross-bars, the legs must have been 
short. To have made the median ridge visible in the bends, the tail would 
have been provided with a pair of side-flaps like those in a lobster, which 
would readily straddle apart as the animal turned round, allowing the sand 
between to rise in a ridge. All these characters render it likely that the 
