PLATE 38 



Ptyctodus howlandi, n. sp. 



Figs. I, 4, 5. Type. Left lower dental plate, X about |. E 1919, p. 112. 

 I, outer view; 4, inner view; 5, oral view (the anterior downward). 



Fig. 2. Left lower dental plate, X f . E 2426, p. 115. 



Fig. 3. Enlargement of surface view of tritoral area of type specimen. 



Fig. 6. Right lower denta plate, natural size, showing tritoral area. E 2421, p. 115. 



■274 



