FOSSIL FISHES. 63 
large and round as to give a peculiar aspect, which will strike the most casual 
observer. On the other hand, the character of the posterior end of the body 
is precisely the same as in Catopterus, and the anterior margin of each fin is 
set with the numerous divergent fulera which are so characteristic of that 
genus; but in the species under consideration they are more numerous, 
shorter, blunter, and more divergent. Hence we must conclude that if this 
fish represents a different genus it is still very closely allied to Catopterus. 
Sir Philip Egerton, as cited by Lyell,’ alludes to fragments of another 
and larger species of Dictyoryge from Chesterfield County, Va. This I sup- 
pose to be the same fish as that represented by some fragments I have from 
that region. It was a much larger fish than D. macrura and the divisions of 
the fin rays were marked by several raised lines, constituting a peculiar 
style of ornamentation. 
Johannes Striiver in 1864 published® a notice of the Fossil Fishes of 
the Keuper, of Coburg, Saxony, in which he describes and figures a spe- 
cies of Dictyopyge (D. socialis) and reviews the structure and relations of 
the genus. With this notice he also publishes a figure and (p. 305) a de- 
scription of another fish associated with the last, Semionotus Bergeri Ag., to 
which I have alluded elsewhere. These figures and descriptions are of 
special interest for comparison with the fishes of our American Trias; for 
it is probable that, if a few good specimens of Ischypterus and Catopterus had 
come into the hands of Agassiz, Berger, Egerton, or Striiver previous to the 
publications of Semionotus, Catopterus, and Dictyopyge, Ischypterus would 
have been united with Semionotus and Dictyopyge socialis have been included 
in Catopterus. Judging from Striiver’s figures it is impossible to designate 
any important character by which these fishes could be generically dis- 
tinguished. Semionotus Bergeri has a dorsal fin which is a little broader 
than that of any of our species of Ischypterus, but in all other respects, even 
to the row of erect and pointed scales on the back, there is the greatest 
similarity between the two genera; nor are there any differences to which 
we can give generic value between Dictyopyge socialis of the Coburg-Keuper 
Sandstein and Catopterus gracilis of Redfield. It is true that in the former 
1Quart. Jour. Geol. Soe. London, vol. 3, p. 277. 
* Zeitschrift Deutsch. geol. Gesellschaft, Berlin, vol. 16, 1864, p. 303-330. 
