NO. 2177. FOSSIL FISHES IN NATIONAL MUSEUM— EASTMAN. 267 



faintly striated denticles, eight in number, extending for a short dis- 

 tance backward from the distal extremity along what corresponds 

 to the antero-inferior margin in the head-spines of modern Cliimae- 

 roids; the postero-superior margin opposite the series of recurved 

 denticles gently reflected. A sudden curve in the direction of the 

 spine takes place about midway its length, by which the distal por- 

 tion of the shaft becomes deflected at right angles from the proximal 

 portion. At the point where the abrupt curvature begins along the 

 antero-inferior margin is seen a prominent semicircular Imob-like 

 expansion, wliich probably served for the attachment of muscles 

 operating to depress the clasper. Surface of spine smooth through- 

 out, but under the lens minute pittings are seen. Ci'oss-section 

 more or less oval, somewhat flattened. 



The type and only known example of this species was collected by 

 Dr. G. Hambach in the St. Louis limestone, near St. Louis, Missouri. 

 It was acquired by the United States National Museum a few years 

 ago, and is catalogued as No. 8095. 



Genus ORACANTHUS Agassiz. 



The spines belonging to this genus often attain a very large size, 

 are much laterally compressed and triangular, rarely elongated and 

 slightly arched; internal pulp-cavity very large, base of insertion 

 usually not very deep, sometimes much extended in horizontal di- 

 rection. Sides of exserted portion ornamented by large tubercles, 

 with a tendency to become arranged in transverse series, sometimes 

 fused. 



ORACANTHUS VETUSTUS Leidy. 



Plate 6, fig. 2. 



OracanthtLs vetustus Leidy, Proc. Acad. Nat. Sci. Phila., vol. 7, 1856, p. 414, and 

 Journ. Acad. Nat. Sci. Phila., [2] vol. 3, 1856, p. 161, pi. 16, figs. 1-3.— 

 Newberry, Trans. N. Y. Acad. Sci., vol. 16, 1897, p. 285, pi. 22, fig. 3. 



The peculiar characters of the much extended base in the spines 

 belonging to this species remained unsuspected untU the publication 

 of Newberry's posthumous paper in 1897, in which a single large and 

 nearly complete spine was described and illustrated. In the same 

 article is given a review of the principal Hterature of the genus, and 

 more complete bibhographical references are brought together in 

 J. W. Davis's monograph on Fossil Fishes of the Carboniferous Lime- 

 stone (pp. 525-526). 



The interesting specimen figured by Newberry was obtained from 

 the Kinderhook limestone near Burhngton, Iowa. In the Museum 

 collection are two remarkably perfect specimens from the same hori- 

 zon at Le Grand, Iowa, one of which is shown in plate 6, figure 2. 

 Some differences are to be noted in the detaUs of ornamentation of 

 the spines that have been referred to this species, but they are not 



