FOSSIL FISHES. Hill 
the head quadrate, often toothed, near the tail long lozenge-shaped, acute. 
Along the middle line of the back runs a row of somewhat larger ovoid, or 
polygonal scales of peculiar form. The surface of most of the scales is 
smooth and polished, but in some species those on the sides near the head 
are marked with oblique raised lines, and in one species the surface is 
occupied by lines parallel with the margin and converging to the posterior 
point. 
The most striking peculiarity of this genus is the posterior position of 
the dorsal fin, a character which suggested the name given it by J. H. Red- 
field. 
The species of Catopterus are among the most beautiful of fossil fishes ; 
the outline is graceful, the head bones are crowded with ornamentation, the 
scales highly polished, often serrate or toothed on the posterior margin, and 
decorated with parallel or concentric raised lines. The fins are long, grace- 
ful, and flowing; the pectorals are faleate and acute, the first rays very 
strong, and thickly set with short fulera, which give it a serrate appearance 
The margins of the other fins are decorated in the same way, so that the 
genus may be recognized by even a fragment of afin. The fin rays are 
very numerous and frequently articulated, the joints flattened and highly 
polished, so that in the fossil state the form and structure are often beauti- 
fully preserved and never fail to excite admiration in the observer. 
No species of Catopterus has yet been found in the Mesozoic rocks of 
the Old World, or, at least, no fossil fish has yet been identified as such In 
eastern America, however, during the latter part of the Triassic age, two or 
three species were exceedingly numerous in the lakes and estuaries of the 
Atlantic coast. In New Jersey and the Connecticut Valley the species of 
Catopterus are fewer than of Ischypterus, and the number of individuals 
is on the whole less, but in some localities the two genera are about equally 
represented. They may be distinguished at a glance, even when minor dif- 
ferences are not shown, by the position of the dorsal fin. In Ischypterus 
this is always anterior to the anal, while in Catopterus it is either opposite 
or posterior. 
Since the above description was written I have received from $. W. 
Loper, of Durham, Conn., some specimens, which enable me to add some- 
