164 



Annals of the Carnegie Museum. 



these, and I am not at all confident that they are interclavicles, but 

 where else will they go? One thing is very evident, they are not 

 penis bones, and I do not see how they can be hyoids, unless they are 

 very different from the Platecarpus type. It looks almost as though 

 there may have been articular facets towards the roughened end, and 

 that would point perhaps toward the possession of clavicles. Of 

 course the ancestors of all the Mosasaurs had both clavicles and inter- 

 clavicles, and their loss was the result of aquatic adaptation. I regard 

 Mosasaurus as one of the least specialized genera of the group, and 

 should expect therefore clavicles and interclavicles to possibly occur. 



" In any event I certainly, if I were you, would publish a figure and 

 description of each bone, for they have a bearing on the phylogeny 

 and classification of the creatures." 



Acting upon the suggestion of Dr. Williston I herewith give a brief 

 description of the two specimens. 



I. Bone Found Associated with the Skeleton of Mosasaurus 

 Lemonnieri Dollo. 



The bone is long, thin, flattened, bifid at one extremity, and at the 

 opposite extremity, which is manifestly not well preserved, but some- 



Fig. 1-3. Bone belonging to Mosasaurus lemonnieri Dollo. I. View of that 

 surface which is both longitudinally and laterally concave. 2. View of that surface which 

 is longitudinally and laterally convex. 3. View of the bone from the side, showing 

 its curvature, the lower edge of the figure corresponding to the surface shown in Fig. 

 2, and the upper edge of the figure corresponding to the surface shown in Fig. 1. 

 14 natural size. 



