■516 RICHARD SWANN LULL ON 



Platypterna deaniana E. Hitchcock. 

 Platypterna deauuinuti E. Hitclicuck. '45b. p. 25; '58, p. So, pi. 14, fiu-. 4. 



Specific characters. Pes: divarication of digits II and III, 40° to 4-3°; of III and IV. 

 25° to 30°; of II and IV, 60° to 70°. Length of digit II, .038 in.; of III, .07(3 m.; of IV, 

 .051 m. Heel: length, .030 m.; breadth. .023 ni. Distance between lateral tips, .0-31 to 

 .063 m. Length of foot, .100 to .115 ni. 



E. Hitchcock ('65, p. 2) speaks of this form as of doubtful validity, possibly because 

 of its probable identity with SlUhuanius tetradactylus. 



The type specimen is no. % of the Hitchcock cabinet, on fine red shale from 

 Weathersfield, Connecticut. 



Platypterna concamerata (E. Hitchcock). 



Harpedactylus concmneratus E. Hitchcock, '48, p. 207, pi. 14, fio-. 3. 

 Platypterna varica E. Hitchcock, '58, p. 85, pi. 14, fig. 8 ; pi. 47, fig. 4. 



Sjjecfic characters. Pes: divarication of digits II and HI, 23°; of TIT and IV, 52°; 

 of II and IV, 75°. Length of digit II, measured from the middle of the heel, .076 m.; 

 of HI, .01)1 m.; of IV, .051 m.; of the heel, .028 m. Width of heel, .050 m. Length of 

 foot, .127 m. Distance between lateral tips, .094 m. Length of step, .200 to .300 m. 

 Width of trackway, .280 m. 



This form is peculiar in the size and breadth of the heel and the cur\'ature of the 

 toes. It is also remarkable for the extreme width of the trackway as the specific name 

 impUes. 



The type specimen is no. ^, of the Hitchcock cabinet, on graj- micaceous sandstone 

 from Turner's Falls, Massachusetts. 



Platypterna digitigrada E. Hitclieock. 

 Platypterna digitigrada E. Hitchcock, '58, p. 86, pi. 14, fig. 9; pi. 51, fig. 2. 



Specific characters. Pes: divarication of digits II and III, 43°; of HI and IV, 37°; 

 of II and IV, 80°. Length of digit II, .020 m.; of III, .030 m.; of IV, .023 m. Distance 

 between lateral tips, .040 m. Length of foot, .050 m.; width of heel, .020 m. Length of 

 step, .100 to .115 m. Width of trackway, .076 m. Toes curving inwards; thick, with 

 acuminate claws. 



This track is analogous to that of Platyj^tenia gracillinia. that is, a further caving of 



