EASTMAN: FOSSIL LEPIDOSTEIDS. 69 



gar ever brought to light. It lacks auy positively archaic features and 

 bears close resemblance to living forms. It is obviously the direct 

 progenitor of the modern Alligator gar, L. tristcBchus (Bloch and 

 Schneider), and compares with it very favorably both in size and general 

 characters. But if we inquire into the more remote or pre-Eocene history 

 of Lepidosteids, palaeontology gives us no answer. They blossom forth 

 suddenly and fully differentiated at the dawn of the Tertiary without 

 the least clue to their ancestry, unheralded and unaccompanied by any 

 intermediate forms ; and they have remained essentially unchanged ever 

 since. 



Lepidosteus atrox Leidt. 



Plate 1, Fig. 3; Plate 2. 



1873. Lepidosteus atrox Leidy, Proc. Acad. Nat. Sci. Phil., p 73. 



1873. Lepidosteus atrox Leidy, Kept. U. S. Geol. Surv. Territ., Vol. I., p. 189, 



Plate XXXII, Figs. 14, 15. (Vertebra.) 

 1873. Clastes atrox Cope, Ann Kept. U. S. GeoL Surv Territ., 1872, p 634. 

 1873. Clastes anax Cope, loc. cit., p. 633. 

 1884. Clastes atrox Cope, Kept. U. S. Geol. Surv. Territ., Vul. Ill, p. 54, Plate II, 



Figs. 1-24. 

 1884. Clastes anax Cope, loc. cit., p. 53, Plate II, Figs. 50-52. (Cranial bones.) 

 1900. Lepidosteus atrox Eastman, Geol. Mag [4], Vol. VII, p. 57 



Definition. — A large species, equalling the recent Alligator gar in size and 

 resembling it in general characters. Head contained about four times in total 

 length ; snout short and broad. External bones very heavy, ornamented with 

 ramifying lines of ganoine tubercles which become consolidated into more or 

 less radiating ridges on the operculum and suboperculum. Jaws with an outer 

 series of numerous small teeth followed by a single series of large, regularly 

 .spaced, conical, striated teeth implanted vertically in a rather deep and narrow 

 furrow. Dorsal and anal fins remote, nearly opposed ; caudal only slightly 

 convex; pelvic situated about midway between the pectorals and anal. Dorsal 

 fin-rays 8, caudal 12, anal 8, pelvic 6. Fulcra biserial and prominent on all 

 fins. Scales \erj robust, in 18-20 longitudinal series, and between 50 and 60 

 oblique transverse series counting along the lateral line. Surface of scales 

 smooth or with feeble ornamentation, consisting of pittings and papillse; 

 posterior margin fimbriate, especially so in scales of abdominal region. 

 Post-cla"sacular scales prominently sculptured. 



Preservation. — Except for the head, the specimen is very well preserved, 

 and the fin-rays remarkably so. Two thirds of the fish, including the head, lies 

 squarely on the ventral surface, but in the abdominal region the body is 

 twisted, so that the right lateral aspect is exposed from the tip of the tail to a 

 point midway between the anal and pelvic fins. The squamation is somewhat 



