NO. 2036. SOME NEW AMERICAN PYCNODONT FISHES— GIDLEY 



449 



ANOMCEODUS MISSISSIPPIENSIS, new species. 



Type. — Posterior portion of right splenial with four teeth of the 

 principal row and three of the outer flanking row. (Cat. No. 75, 

 U.S.N.M.) See fig. 6, p. 449. 



Locality. — Guntown, Mississippi. Probably from deposit of Cre- 

 taceous age 



Description. — Larger than A. latidens. Teeth of principal series 

 less wide as compared with anteroposterior 

 length and more decidedly expanded at their 

 outer ends; teeth of flanking series triangulate, 

 relatively large and opposite the interspaces of 

 the principal series as in ^. latidens. The teeth 

 of the principal series are closely set together 

 as in the latter species, but are less sharply 

 convex fore and aft and are even more broadly 

 expanded at their outer ends. The teeth are 

 hollow beneath. This character, however, may 

 have no significance peculiar to the species. 



Comparative measurements of largest tooth in 

 principal series of splenial plates described by 

 Leidy and the two species of this genus here 

 reported are given below. 



Fig. 6.— ANOMCEODUS mis- 

 sissiPPiENsis. Type. 

 Portion or right sple- 

 nial. Nat. size. 



Specimens of Pycnodont fishes in American deposits are compara- 

 tively rare and consist for the most part of fragments of vomerine 

 and splenial plates on which a few teeth, or in some instances only 

 their bases, have been preserved. Several of the specimens in the 

 United States National Museum collection here described are more 

 than usually complete and for that reason have been carefully and 

 fully figured. The specimens referable to Microdon are especially 

 important in that they record for the first time the presence of this 

 genus in deposits of this continent.^ 



Cope once referred to this genus a specimen from the Lower Creta- 

 ceous of Texas, wliich he called Microdon dumhelli but afterward 

 assigned to the genus Mesodon.^ 



1 Cope, Proc. Amer. Philos. See, 1892, p. 128 {Microdon dumhelli). 



2 Joum. Acad. Nat. Sci. Phila. (2), vol. 9, 1895, p. 444. (Mesodon dumbelli) Mesodon (preoccupied) =■ 

 Typodus according to Hay, Bull. 179, U. S. Geol. Survey, 1902, p. 372. 



95278"— Proc.N.M.vol.46— 13 29 



