PLATE II. 



PAGE. 

 Fig. i PSEPHODUS LATUS, St. J. and W 72 



1 a. A small mandibular median tooth, seen from above, part of the coronal sur- 

 face bordering the inner margin broken away; 1 1>. do., transverse profile 

 from inner margin; 1 c. do., from outer margin; 1 d. do., postero-lateral 

 border; 1 e. do., antero-lateral border, showing longitudinal profile. St. 

 Louis limestone; Alton, Illinois; Mr. Van Home. 



Fig. 2, a, b. c. d. e. Similar views of a very small example of the same form, left 

 ramus, enlarged; 2/. do., inferior surface. Same formation, locality and 

 collection. 



Fig. 3 a. A serial tooth, view from above; 3 b. do., outer margin transverse profile; 3 c. 

 do., from the postero-lateral (?) border, longitudinal profile. St, L.; St. 

 Louis, Missouri. 0. St. John. 



Fig. 4. PSEPHODUS LUNULATUS, St. J. and W 74 



Fig. 4 a. Views of tooth from above; 4 b. do., from the lateral border; 4 c. do., inner 

 margin; 4 d. do., from the outer margin. Chester limestone; Chester. 

 111. Dr. George Hambach. 



PSEPHODUS PLACENTA. St. J. and W 69 



Fig. 5 a. A mature tooth referred to right ramus of mandible, from above; 5 b. do., 

 * from inner margin; 5 c. do., views from the anterior and the posterior 



border. Upper fish-bed, Kinderhook ; Burlington, Iowa. Mr. "Wachs- 



mutn. 

 Fig. C a. c. c. d. Similar views of a smaller tooth, occupying the same position upon 



the jaw as the last. Same horizon and locality. Prof. Worthon. 

 Fig. 7 a. I. c. d. Similar views of an elongate individual of left ramus of upper jaw. 



Same formation, locality and collection. 

 Fig. 8 a. b. c. d. The same views of a small, short median tooth, referred to the right 



ramus of upper jaw. the coronal region much worn in front (the original 



of Helodus placenta). Same horizon, locality and collection. 



