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ART. XIII. — Descriptions of some remains of fishes from the Carboniferous and 



Devonian Formations of the United States. 



By Joseph Leidy, M. D. 



EDESTUS, Leidy. 



Generic Characters. — Maxillary bones segmented ; segments beveled anteriorly and 

 excavated posteriorly for coadaption. Teeth in general form resembling those of 

 Charcharodon ; one coossified with each maxillary segment. 



Edestus vorax, Leidy. 



Proc. Acad. Nat. Sci., vii, 414. The subject of the present description is a fossil 

 fragment of the jaw of a remarkable and gigantic fish, which was presented to the 

 Academy by William S. Vaux, Esq., who obtained it from an itinerant showman. The 

 latter informed Mr. Vaux, that the specimen was discovered at Frozen Rock, Arkansas 

 river, twenty miles below Fort Gibson, in the Indian Territory. 



The specimen is dense, heavy, and jet-black ; and when it was first received the 

 crevices about its surfaces were filled with carbonaceous matter. It was probably 

 derived from a coal bed ; but the geological features of the locality from which it was 

 obtained I have been unable to learn. 



The fragment of jaw is six inches in length ; and it measures three inches in depth 

 from the dental border. The sides are symmetrical, and slope divergently from the 

 latter position towards the base, which is convex and moderately keeled in the median 

 line. At the dental border the jaw is about seven eighths of an inch in thickness, and 

 and at the thickest part of its base measures one inch and four-fifths. Longitudinally 

 the base of the jaw is slightly concave and furrowed. The surface of the bone is 

 covered with fine vermicular, reticulating, broken ridges, assuming a striking resem- 

 blance to arabic writing. 



The most remarkable peculiarity of the jaw is its segmented character; and of the 

 segments the fossil retains two very nearly perfect ones with portions of two others. 

 Each segment in outline forms an irregular pentahedron ; and each jiossesses a single 

 coossified tooth, whose broad surfaces abruptly increase the acclivity of the sides of 

 the jaw. 



From its general form the fossil might readily be taken for a portion of the lower 



jaAV, but from the fact that no vertebrated animal, neither living nor extinct, has jet 



been discovered in which the dental branches of the inferior maxilla are segmented, 



while several genera are known, as the Lepidosteus anions; living fishes, and the 



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