394 O. C. Marsh on new Mosasauroid Reptiles 
Length of crown and osseous support, 1 inch, 11° lines. 
Length of crown alone, Ios 4% 
Antero-posterior diameter of crown at 
ok ec then Ded ik alah ye iin a inte pelo 535 * 
Transverse diameter of crown at base, 4: 
The fang-like supports of all the teeth are more firmly cods- 
sified with the jaws than is usually the case in this family, and 
most of them contain excavations for the successional teeth. 
On the outer superior edge of the lower jaws there is a row of 
its, round or oval in outline, and alternating with the teeth. 
a most instances one is situated outside and a little in front of 
each tooth, and those in the anterior portions of the jaws are 
leeper than those farther back. They evidently have been ex- 
eavated by the maxillary teeth, and are adapted for their recep- 
tion, like the similar cavities in the jaws of crocodiles. Slight 
depressions, corresponding to these in position, may be seen in 
the jaws of some of the larger species of Mosasaurus, and the 
unusual depth of the pits in the present specimen is probably 
due to the more pointed character of the teeth. 
apertures, and finally very convex as it again expands before 
coalescing with the uate 2 frontal. This fragment indicates that 
the nasal bone was very slender, and, like the premaxillary, un- 
divided; that the superior nasal openings on either side were 
long and narrow, and that the central line of the face immedi- 
ately behind them was marked by a low rounded ridge. 
This species will be easily distinguished from the Mosasau- 
roids hitherto described, with the possible exception of the 
J us accutidens of Gibbes,* which was founded on specimens 
including teeth of Hyposaurus. i tal : 
, and a single den 
re unequally divided by the acute edges, and they also — 
‘olcodus. 4 
The present remains indicate an animal about twenty-five feet ; 
in length. They are from the lower Cretaceous greensand bed q 
_ ® Smithsonian Contributions, vol. II, Art. 6, p. 9. 3 
