KARPINSKY’S GENUS HELICOPRION. 
A REVIEW. 
C. R. EASTMAN. 
IT is a significant and decidedly unwelcome truth that not one 
in one hundred essays on paleontological subjects receives any- 
thing like the elaborate care and finish which Dr. Karpinsky,! 
the. Director of the Imperial Russian Geological Survey, has 
bestowed upon the remarkable ichthyodorulites which he de- 
scribes under the name of *Helicoprion." Within the com- 
pass of 110 pages, enriched by seventy-two text-figures and 
four quarto plates, the subject is treated from all possible 
standpoints — historical, geological, chemical, histological, and 
biological. The result is a very gratifying addition to the 
knowledge of Palzeozoic fishes. 
Helicoprion is a fitting title for the peculiar “spiral saws,” 
coiled in three and a half whorls and armed with upwards of 
150 sharp teeth, which have recently been discovered in the 
Permo-Carboniferous (Artinsk Series) of the government of 
Perm. Although ammonitic in outward appearance, inspection 
shows these bodies to be of elasmobranch nature, the nearest 
allied structures being found amongst the Edestida. A com- 
plete summary of the literature of Edestide is given in the 
first twenty pages, with text-figures of all the more important 
species that have been described. Next follows a discussion of 
the stratigraphic position of the Russian specimens, and finally 
a minute account of their form, structure, and general nature. 
At the end the results of the investigation are tabulated under 
sixteen different headings, and a restoration is attempted show- 
Ing the imaginary position occupied by the spiral during life 
of the creature. Few will be prepared to admit, however, that 
5 Karpinsky, A. Ueber die Reste von Edestiden und die neue Gattung Heli- 
Coprion, Verh. k. russ. min. Ges. St. Petersburg, Ser. 2, Bd. xxvi, No. 2, 1899. 
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