NO. 1870. 



NEW 3I0SASAUR0ID REPTILE— GILMORE. 



483 



Fig. 2.— Inner view of posterior part 



OF RIGHT PRESPLENIAL GLOBIDENS ALA- 

 BAMAENSIS. TYPE-SPECIMEN, J NATURAL 

 SIZE. O, POSTERIOR OR ARTICULAR END. 



Presplenial} — A portion of the posterior part of the right pre- 

 splenial shows that Globidens has the joint in the lower jaw as in the 

 other genera of tliis group. ^ The portion preserved is massive, with 

 the usual cupped articular end. The outer surface is rounded toward 

 the lower margin, and the articular surface for union with the den- 

 tary approaches close to the posterior end as in Mosasaurus. 



The upper side of tliis end is U- 

 shaped in section, \\dth each side ex- 

 tendmg upward as a thin margin, the 

 hmer portion being higher and heavier 

 than the outer. Thirty millimeters 

 from the posterior end on the inner 

 side is a large foramen (see fig. 2), 

 extending forward into the groove for 

 Mechel's cartilage. The anterior part 

 of tills bone is missing. The articidar 

 end has a transverse uddth of 27 mm. 



Vertebra. — There is only one vertebra preserved with this speci- 

 men and though imdistorted by pressure the processes of tliis bone 



have been much 

 damaged. Its chief 

 characteristics are 

 well shown in fig- 

 ure 3. 



The presence of 

 heavy transverse 

 processes and a ru- 

 cUmentaiy hypapo- 

 pliysis indicates this 

 vertebra to be one 

 of the posterior cer- 

 vicals, probably the 

 sixth. 



In the general pro- 

 portions of the cen- 

 trum it resembles 

 the vertebrae of 

 Platy carpus more 

 nearly than anj^ of the other genera with which it was compared. 



1 Presplenial of Williston; splenial or opercular of other authors. 



2 Williston (Univ. Geol. Surv. Kansas, vol. 4, 1898, pp. 212-213) has discussed at some Icngtli the use of 

 the peculiar ball and socket articulation at the middle of the lower jaw, and concludes that, in the true 

 mosasaurians, it is 1 o allow the lateral expansion of the jaws when swallowing large objects. It is of interest 

 to note in this specimen a similar articulation, although, as indicated by the dentition, the food must have 

 been of quite a different nature, and the use of such a joint is not easily accounted for. 



Fig. 3.— Posterior cervical vertebra of Globidens alabamaen- 

 sis, (a) laterial view; (6) ventral view; (c) posterior view; 

 (d) anterior view. Type-specimen, J natural size. 



