74 BULLETIN': MUSEUM OF COMPARATIVE ZOOLOGY. 



Lepidosteus simplex Leidy. 



Plate 1, Fig. 1. 



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

 1873. Lepidosteus simplex Leidy, Rept. U. S. Geol. Surv. Territ., Vol. I., p. 191, 

 PI. XXXII, Figs. 18, 26, 31-43. (Vertebra, jaw-fragraents, scales.) 



For the opportunity of describing this interesting specimen the writer is 

 indebted to Mr. F. A. Lucas, who obtained possession of it in behalf of the 

 United States National Museum after it had passed into oblivion since being 

 exhibited by a private collector at the Chicago World's Fair. It was derived 

 originally at the typical Green River locality in Wyoming, and bears the 

 catalogue number 4754. 



The specific determination is based principally on scale characters, the 

 enamel surface of the few detached scales known to Leidy being described by 

 him as " flat, smooth, and highly polished, and exhibits no markings except 

 one or several minute punctae near the centre." One peculiar scale, which we 

 can now recognize as belonging to the lateral line and oriented in a wrong 

 position in Plate XXXII, Figure 33, of Leidy's Monograph, is described (Rept. 

 U. S. Geol. Surv. Territ., Vol. I, p. 191) as "traversed fore and aft by a canal 

 communicating by a short cleft with the outer surface. The cleft is directed 

 backward, and is protected by an angular elevation of the anterior border." 

 It would appear to be characteristic of this species that scales of the lateral line 

 are traversed by short vertical canals instead of horizontal clefts, and the 

 remaining scales are flat, smooth, and polished with entire edges. Other dis- 

 tinguisbing features will be noted presently, and the definition may be emended 

 as follows : — 



Definition. — A species attaining a total length of about 65 cm., of which 

 the head forms one fourth. External bones not especially heavy, arranged as 

 in the recent Alligator gar, but with finer and more granular ornamentation ; 

 the ganoine tubercles of operculum and suboperculum forming more or less 

 continuous lines, as in L. atrox, but those of the interoperculum fused into 

 irregular ridges. Jaws with an outer series of numerous small teeth followed 

 by a single series of larger ones, the latter, however, relatively of much less 

 size than in L. atrox. Vomers dentigerous, but no teeth observed on either 

 palatines or parasphenoid. Fins as in L. atrox, but relatively weaker, and 

 dorsal and anal more remote. Scales smooth and highly polished, with entire 

 margins and no ornamentation save for occasional minute puncta; near the 

 centre; scales of the lateral line cleft by a short vertical canal. At least 45 

 oblique transverse scale-series, and 18 to 20 longitudinal ones. Flank-scales 

 of posterior part of the body considerably elongated in an antero-posterior 

 direction. 



Description. — The total length of the fish when straightened out was probably 

 not far fnjni 64 or 65 cm., or e.\actly four times the length of tiie head in the 

 Hicdian liue. In L. atroc and L. tropicits the head is also contained four times 



