165 



for Meckel's cartilage is very large, and is exposed below the last two teeth, 

 as the splenial terminates at the third. Two series of foramina on the exter- 

 nal face of the ramus. There are alveolae and bases for thirteen teetli on the 

 dentary bone. This, it will be observed, is one more "than in M. gracilis Owen, 

 and one less than in other species of Mosasaurus. The posterior extremity 

 of the dentary shows its marks of reception into the notch of the coronoid ; 

 it is more compressed and less club-shaped than the corresponding part 

 of L. mitchittii, and would indicate less lateral flexibility than in some other 

 types. 



The right palatine is of less elongate form than in some other species. 

 It presents the sutnral face for union with the maxillary on the outer anterior 

 extremity, and narrows to an apex a little in advance. The dentigerous face is 

 widest at the anterior third of the length, where the outer margin is expanded. 

 This then contracts, and is compressed vertical at the tenth tooth, where it is 

 broken off. The transverse process is given off a little anterior to the ninth 

 tooth. The interior face of the bone is a vertical plane, without projection, 

 except a slight obliquity at the anterior extremity ; and it is clear that there 

 has been some interval between this palatine and its fellow. The superior 

 margin is obtusely rounded. 



The bases of the palatine teeth are exposed for two-thirds their length on 

 the outer side of the bone. The antero-median are large, and the anterior 

 most closely placed. Their crowns are strongly recurved, round in section, 

 and with a fine sculpture of straight striae, most marked near the base and on 

 the inner side. They are more spaced posteriorly than any other species 

 except L. mitchittii, and are relatively larger than in any except the same 

 species. They have not the compressed form with basal shoulder character- 

 istic of the M. dekayi. 



Measurements of the muzzle. 



Iucbos. 



Length of the fragment 31. 



Length from the end of the muzzle to the prefrontal 21.5 



Length from the end of the muzzle to the nares .- 11.75 



Length from the end of the muzzle to the maxillary 5.75 



Length from the end of the muzzle to the first tooth 2. 5 



Width of the muzzle at the end 1.5 



Width of the muzzle at the anterior extremity of the nares 8, 



Width of the premaxillary at the anterior extremity of the nares 3.3 



Width of the maxillary between the tenth and the eleventh tooth r 3.2 



Depth of the mandible at the extremity «. 2.5 



Depth of the mandible at the sixth tooth 3. 5 



Depth of the palatine at the transverse process : 2.5 



Width of the palatine at the transverse process 1.4 



