THE SILURIAN BEACH. 
Pikes of our Western waters, though the Stur- 
geons share also in some of their features. In 
these fishes there is a singular union of reptilian 
with fisli-like characters. The systems of circu- 
lation and of respiration in them arc more com- 
plicated than in the common fishes ; the struc- 
ture of the skull resembles that of the skull in 
reptiles, and they have other reptilian characters, 
such as their ability to move the head upon the 
neck independently of the body, and the connec- 
tion of the vertebrae by ball-and-socket joint, in- 
stead of by inverted cones, as in the ordinary 
fishes. Their scales are also peculiar, being cov- 
ered by enamel so hard, that, if struck with steel, 
they will emit sparks like flint. It is on account 
of this peculiarity that the whole group has been 
called Ganoid. Now, though we have not found 
as yet any complete specimens of Silurian fishes, 
their disconnected remains are scattered profusely 
in the early deposits. The scales, parts of the 
backbone, parts of the skull, the teeth, are found 
in a tolerable state of preservation ; and these in- 
dications, fragmentary as they are, give us the 
clew to the character of the most ancient fishes. 
A large proportion of them were no doubt Gan- 
oids ; for they had the same peculiar articulation 
of the vertebrse, the flexibility of the neck, and 
the hard scales so characteristic of our Gar- 
Pikes. 
