300 



The two marginal bone's are longer than wide and quite thin. The 



proximal margin is obtuse, rugose, and but little thickened, and exhibits near 



the end in each bone a small oval fossa for the extremity of the rib. The 



external margin is thin and sharp, and is produced into a prominent angle near 



the middle in each bone. This presents a right angle partially backward, 



and is thin-edged. The bone is dense, and there are no indications of 



scutal sutures. 



Ileasiirements. 



M. 



Leugth of the dentary bone 048 



Width above 0.009 



Depth ou the inner side at the middle 0.007 



Width of the maxillary O.OU 



Depth of the maxillary on the outer side 0. 008 



lutcrorbital width 0.016 



Width of the sphenoid at the middle 0.016 



Antero-posterior width of the quadrate above 0. 016 



Depth of the quadrate externally 0. 021 



Length of a marginal 0. 048 



Width of a marginal 0.033 



Depth of a marginal proximally 0. 006 



The characters displayed by this species ally it to the genera of the 

 New Jersey greensand, as Osteopygis, etc., which, as I have pointed out, 

 possess characters of both the Chelydridce. and the CheloniidcE. The super- 

 ciliary border of the frontal, with the extent of the prefrontals, with the indi- 

 cations of a short temporal roof, are characters of Chelydra. The absence of 

 dermal scutal sutures distinguishes the genus from Catapleura, Osteopygis, 

 etc. The stouter and deeper dentary bone strongly distinguishes the species 

 from Toxochelys latiremis, Cope (see p. 98). 



PISCES. 



Enchodu.s dolichus. Cope, supra, p. 239. 



Several additional specimens of this fish exhibit the following charac- 

 ters: No. 1 shows that the long premaxillary tooth has a cutting-edge on the 

 posterior side of the apex extending one-fourth the length, and directly oppo- 

 site the anterior edge. The surface of this and of the maxillary teeth is not 

 sulcate, but striate, and with a silky luster. The maxillary teeth, as in other 

 species, diminish in size posteriorly, and display two cutting-edges nearly to 

 the base. In No. 2, the dentary bones of both sides are preserved. These 

 display a series of small, acute teeth on the outer alveolar margin, which 

 passes round the outer side of tiie larger anterior flings to the end of thi' 



