AVillistox.] Mosasaurs. 191 



PliopJatecarp us. 



Plinplafecarpus Dollo, Note sur l'osteologie de Mosaeauridse, Bull. Mus. 



Roy. Hist. Nat. Belg., i, 1882, p. 62. 

 Oterognathua Dollo, Premier Note sur les Mosaeauriens de Mesvin, Bull. 



Soc. Belg. Geol. Pal. Hydr., in, 1889, 286. 



Preniaxillary obtuse, not projecting beyond the teeth. Teeth 

 long and slender, faceted and striated. Suprastapedial process 

 of quadrate long ; ear cavity large. Mandible slender, the cor- 

 onoid rudimentary. Chevrons free, not large. Coracoid 

 emarginate. An interclavicle present. Humerus stout. Zyg- 

 osphenes rudimentary. Type species, P. marsliii Dollo, 1. c. 

 Maestrichtian. 



This genus was originally made the type of a new family, 

 based upon the supposed union of vertebrae to form a sacrum. 

 This was afterwards found to be an error by the author and the 

 family withdrawn. The genus certainly belongs in the vicinity 

 of Platecarpus, though abundantly distinct, especially in the pe- 

 culiar shape of the limb bones, as figured, in the mandible, etc. 



Progna t h osaurus. 



Pror/nathosaurus Dollo, Premiere Note sur le Mosasauriens de Mesvin, 

 Mem. Soc. Belg. Geol., in, 293, 1889. 



Premaxillary short, not projecting beyond the teeth. Frontal 

 large and triangular. Prefrontal and postfrontal touching each 

 other. Sclerotic ring conical. Pterygoid with very large teeth. 

 Quadrate with the suprastapedial process strong, coossified with 

 the infrastapedial process below, inclosing an oval auditory 

 meatus. Mandible strong, more or less campylorhynchous, 58 

 with a large coronoid process. Parietal foramen of moderate 

 size. Hypapophyses of cervical vertebrae free. No zygosphene ; 

 chevrons articulated. Coracoid without emargination. Typ- 

 ical species, P. solvayi Dollo, 1. c. Brown Phosphatic Chalk of 

 Cipley, Upper Senonian. 



58. That is, curved, with its upper border concave. 



