1911] 



Merriam and Bryant: Omphalosaurus. 



331 



teriorly on each element the teeth decrease in size. The area 

 having the best preserved teeth shows them in irregular rows. 

 There are at least five rows anteriorly, but only three distinguish- 

 able at the posterior extremity of the element. This arrange- 

 ment, however, is not so apparent on the rest of the dentigerous 

 area, where the teeth are broken off or are crushed together. No 

 part of the elements exposed appears to be edentulous, teeth 

 being found out to the margins. 



Fig. 2. Omphalosaurus (?) , sp. Portion of a dentition in which the 

 teeth show a tendency toward a low-conical form. No. 19453, natural size. 



The other specimen (no. 19453) apparently shows several of 

 the bones belonging to the skull, and the cross-section of an 

 element bearing nine or ten teeth similar to those on the type 

 specimen. 



As nearly as can be determined on the omphalosaur-like 

 material available the teeth rest in distinct pits. The pits vary 

 from two to six millimeters in depth and from three to fifteen 

 millimeters in greatest diameter. In all cases the depth of the 

 pit is less than the greatest transverse diameter, and is nearly 

 the same as the height of the tooth-crown. 



The crowns are quite uniformly dome-shaped, with a nearly 

 circular cross-section. The largest tooth measures fifteen milli- 

 meters in greatest transverse diameter. The enamel does not 

 appear to be perceptibly roughened. The short, bluntly-conical 

 roots show no radial folding of the dentine as in the ichthyosaurs. 



