Cope.] 2'*^ [Xov. 5, 



fers from tlie E. ferox, wliere the section is lenticular, the base triangular 

 ovate, the outer face widening downwards and no grooves. In E. pressi- 

 *dens the base of the tooth projects well beyond the anterior margin of 

 the front of the premaxilliary, while in the E. ferox the reverse is the 

 case. Length of tooth 20.5 lines ; transverse width at base 6 lines; lon- 

 gitudinal do. 3.7 lines. Length premaxilla 31.8 lines, depth 15.5. 



Two specimens from the cretaceous green sand of New Jersey. 

 Pneumatosteus, Cope. 



This genus is established on a caudal vertebra of peculiar character, 

 It is opisthocoelian, and without trace of suture of either neural or haemal 

 arches. The elements constituting the haemal arch appear to be dia- 

 pophyses ; they are divergent, and probably do not unite distally ; they are 

 directed more posteriorly than anteriorly. Their proximal boundary is 

 apparently indicated by an indistinct elevation, perhaps the position of 

 the original suture. The neural arch is split above by a deep median 

 anterior fissure, on each side of which the narrow zygapophyses diverge. 

 There is no zygantrum. The base of the broken neural spine is very 

 small, and is as long as wide; it may probably have had but little eleva- 

 tion. 



The structure of the bone is exceeingly light, and the external osseous 

 layer very dense. In order to reduce the weight consistently with the 

 size, the lateral and inferior faces are excavated by deep concavities 

 terminating in pits. There are two on each side separated by a longitu- 

 dinal ridge-like septum, Avhich is plane with the expanded rims of the 

 cup and ball. The superior pits are beneath the base of the neural spine, 

 and nearly meet under the floor of the neural canal. The inferior con- 

 cavity is very large, and extends from rim of cup to ball, and is divided 

 longitudinally by a thin laminar hypapophysis. The bases of the diapo- 

 physes are wide, and extend from the base of the ball, three-fourths tlie 

 distance on each side to the rim of the cup. 



The form of the vertebra is compressed. The ball is more convex 

 transversely than vertically, and presents a slightly double convexity in 

 profile. This is produced by a slight transverse contraction at the in- 

 ferior fourth of the vertical diameter. The floor of the neural canal is 

 raised to the superior margin of the ball. 



This vertebra resembles the fourth in advance of the flrst bearing 

 chevron bone in Lepidostues. It difiers from it generically, solely in the 

 completeness of the neural arch abone, since it is longitudinally fissured 

 in the existing genus. 



Pneumatastetjs nahunticus. Cope. 



The specific characters of this fossil are as follows : The cup is a verti- 

 cal oval, slightly truncate below, and openly concave truncate above. 

 Its form is not unlike that seen in soine of the Pythonomopha. The neu- 

 ral arch is much contracted transversely opposite the neural spine. The 

 surface of the bone is very smooth, except a few slight rugae near the rim 

 of the cup. 



