Cope. ] 42 [March 3, 
but one, an anterior, cutting edge, the posterior face being regularly 
convex. The inner face is much more convex than the outer, and the 
flatness of the latter is marked at the apex of the tooth by a short ridge 
which bounds it posteriorly. This is a trace of the bounding angle which 
extends to the basis of the crown in Mosasaurus. ‘lhe anterior cuttin 8 
edge is in profile convex ; the posterior outline concave to near the tip. 
The cutting edge is acute, and beautifully ribbed on each side, but not 
properly denticulate. The surface of the tooth is not facetted, but the 
outer face exhibits the peculiarity of a longitudinal concavity, or shallow 
gvoove extending from the base to the middle of the crown. The enamel 
is polished, but under the microscope minutely and extensively striate 
ridged. This description is taken from the second or third from the 
anterior end of the maxillary bone. The third from the distal end of the 
‘dentary is very similar. 
The crowns become rapidly more compressed as we pass backwards. 
¥rom a broad oval section of two crown bases, we reach a flattened oval 
crown, with the cutting edge sharp behind as well as before, and minutely 
ribbed. The crown is not facetted, and is more convex interiorly than 
exteriorly. The exterior convexity is chiefly anterior ; the posterior face 
is slightly concave from the open groove already described as present in 
the anterior teeth. In two posterior crowns, one still more clongate in 
‘section, the external concavity becomes flatter and includes a great 
part of the outer face. A tooth still more posterior presents the peculiarity 
-of the species in the strongest light. The crown is still more compressed, 
‘directed backwards, and only .25 higher than wide antero-posteriorly at 
the base. The latter is a little over twice the transverse diameter just 
behind the middle. The surface presents the characters described in 
others. The outer concave surface is wide and shallow, and contributes 
to the attenuation of the posterior half of the tooth rather than the an- 
terior, which is consequently thicker. The cutting edges are sharp, the 
anterior convex and retreatiag backwards to the rather obtuse apex ; the 
posterior convex above, concave below. 
The exposed parts of the dental pedestals are frustra of cones, neither 
swollen nor concave. 
Measurements, M. 
Third superior maxillary length crown............0..0005 0.088 
“height crown and pedestal. .............00cce eu eee 048 
““ Jongitudinal diamcter base crown............0..000 02 
OO SONAMSVORS Oxia cca se anis Saata lente ds naaiels tee W a te 013 
‘ixthidetitiry, lousitudinal.o25 a:acacxvsesasieouss sans 024 
ae ae UUAMISVERSCsia ice 14 45 Shean D aad ans Hiadene gases -014 
Eleventh dentary height crown .........0..c0ce cece eee 084 
és height crown and pedestal.............00.00cee 0505 
ee longitudinal diameter basis crown.............5 026 
ce TRANSVEPSC) aac. ics eeu sg Meee Aes 4s ERE SE Eek 014 
“The articular bone is perhaps .66 the size of that of Mosasaurus dekayi 
