PLATE XX. 



Page. 



COPODUS PUSILLUS. St. J. and W 231 



Fig. 1 a. Maxillary tooth, view from above, outline partially restored, enlarged; 1 5, 

 do., transverse profile from inner margin; 1 c, do., longitudinal profile 

 from the lateral border. Chester; Chester, Illinois. Dr. Geo. Hambach. 



COPODUS VAN HOENII, St. J. and W \u.'j 



Fig. 2 a. Mandibular tooth, view from above, outline partially restored; 2 It, do., from 

 the outer margin; 2 c, do., longitudinal profile from the right border; 2 d, 

 do., inferior surface. St. Louis; Alton, 111. Mr. Van Home. 



Fig. 3 a. Maxillary tooth, from above; 8?*, do., from the anterior margin; 3 c, do., 

 transverse profile from the posterior margin; 3 d, do., longitudinal pro- 

 file from the left border; 3 e, do., inferior surface. St. Louis: St. Louis, 

 Missouri. Mr. St. John. 



PSAMMODUS SPEINGEKI, St. J. and W 202 



Fig. 4 a. Maxillary tooth, right side, view from above; 4 b, do., transverse profile 

 from inner margin; 4 c, do., anterior margin: 4 d, exterior border; out- 

 line showing probable disposition of teeth upon the jaw. Upper Bur- 

 lington limestone fish-bed; Burlington. Mr. St. John. 



Fig. 5 a, b, c. Similar views of a left side tooth of the same form; 5 d, do, articular 

 border. Upper Burlington limestone; Louisa county, Iowa. Mr. St. 

 John. 



Fig. 6 a. View from above of a large example of the same form, outline partially re- 

 stored; 6 b, do., transverse profile from posterior margin; 6 c, do., ar- 

 ticular border. Upper Burlington fish-bed; Louisa county, Iowa. Mr. 

 Springer. 



Fig. 7 a. A similar example of the opposite side, from above; 7 b, do., exterior bor- 

 der; 7 c, do., articular border; 7 d, do., anterior margin. Same forma- 

 tion, locality and collection. 



Fig. 8 a. Mandibular tooth, left side, from above; 8 b, do., posterior margin, trans- 

 verse profile; 8 c, do., anterior margin; 8 d, do., articular border, longi- 

 tudinal profile; 8 e, do., exterior border. Upper Burlington division 

 beds; Quincy. Professor Worthen. 



Fig. 9 a, b, c. Similar views of a specimen of the same form, right side; 9 d, do., ar- 

 ticular border. a*id outline showing inrollment of the mandibular series 

 of teeth from within[outwards. Upper Burlington limestone; Burling- 

 ton. Mr. St. John. 



Fig. 10 a. Mandibular tooth, left side, view from above; 10 b, do., from posterior mar- 

 gin; 10 c, do., from anterior margin; 10 d from articular border; 10 e do., 

 exterior border. Upper Burlington limestone; Louisa county, Iowa. 

 Mr. Springer. 



Fig. 11 a,b, c, d, e. Similar views of a large, proportionately broad mandibular f?)tooth, 

 right side. Same formation, locality and collection. 



