AET. 15 



PLEISTOCENE FOSSIL TURTLES — GILMOKE 



This keel is not continuous but is interrupted at the vertebral sulci 

 sej^arating the scutes; widest at the front of the scute it gradually 

 narrows and completely subsides before reaching its posterior 

 extremity. In specimens Nos. 11,428, 11,330 U.S.N.M., and No. 

 25-144 A. C. there is only the faintest suggestion of a median keel, 

 whereas in No. 25-144 A. C. it is strongly developed at the anterior 

 end, as shown in plate 2. Vertebral one has the center raised into 

 a prominent obtusely rounded elevation that extends longitudinally 

 the full length of the scute. The prominence of this ridge seems to 

 be one of the distinctive features of the species. An incipient ridge 

 is present in T. innoxia^ T. singletoni, and in the living T. major, 

 but none of these show such a conspicuous development as in the 

 species under discussion. 



The vertebrals are relatively long and narrow for a Terrapene 

 resembling T. singletoni in this respect. Their measurements are 

 given in the table below: 



Measurements of vertebrals 



The urnshaped form of the first vertebral is another feature that 

 seems to be distinctive of this species. Anterior of its mid length 

 the scute is strongly constricted as shown in Figures 2 and 3 and in 

 three of the four specimens now before me all have the posterior half 

 of this scute as wide, or wider than the anterior end. Comparative 

 measurements are given in the table below : 



Name 



Greatest 



width 

 posterior 

 to middle 



Terrapene canaliculata: 



No. 25-144 A. C 



No. 25-145 A. C 



No. 11,330 U.S.N.M 



No. 11,428 U.S.N.M 



Terrapene singletoni, type 



Terrapene innoxia, type 



Terrapene longinsulae, type No. 5983 U.S.N.M 



Terrapene major 



Terrapene Carolina 



Mm. 



47 

 49 

 49 

 53 

 36 

 21 

 25 

 30 

 26 



