99 



Measurements. 



M. 



Length of tlio co.acoid 0.250 



WiiilU of tlie coracoiil distally 0.080 



Lenstli of the ramus of the inaudible 0. 157 



Length of the sym)>hy8i8 of the mandible 0. 031 



Elevation of the coronoid of the mandible 0.043 



Width of the- angle of the coronoid 0. 023 



The axes of the mandibular rami produced unite at an angle of 65°, 

 indicating a muzzle of intermediate length. 



The size is about that of the existing loggerhead (Careiia caouand). 

 Found by Professor Mudge near the forks of the Smoky Hill River. 



Fig. 2. — Sketch of the large radiated bone of I'rotostega gigaa, with other elenxMits, as they were 

 uncovered by excavation; size much icductd, drawn on the spot. Nos. I, "Vll, VIII, and IX, costal 

 bones, with the rib-heads looking upward ; X, the coracoid bone ; 5, a marginal bone ; 9 and 10, the lateral 

 a radiate bones; 16, vertebra, with other bone adherent. 



PROTOSTEGA, Cope. 



This genus is the type of a new family of tortoises of the suborder 

 Athccce, characterized by the lack of exj^ansion of the ribs into a ])ony roof, 



