PLATE IX. 



PAGE. 

 DELTODUS PAEYUS. St. J. and W 151 



Fig. 1 a, Mandibular posterior tooth, left ramu=, from above, enlarged ; 1 b. do., pro- 

 file from antero-lateral border; 1 c. do., from postero-lateral border. St, 

 Louis; Pella. Iowa. Mr. St. John. 



Fig. 2 a. Same form, right ramus, enlarged. Same formation, locality and collection. 



Fig. 3 a. Outline of a mandibular median tootb, left ramup, from above, enlarged. St. 

 Louis; St. Louis, Mo. Mr. St. John. 



Fig. 4 a. Maxillary posterior tooth, right ramus, from above, enlarged; 4 b. do., trans- 

 verse profile from inner margin; 4 c. do., longitudinal profile from ante- 

 ro-lateral border, extremity restored in outline. St. Louis, Pella, Iowa. 

 Mr. Van Home. 



Fig. 5 a. 6. c. Similar views of the same form, left ramus. showing a perfect example. 

 Same formation and locality. Mr. St. John. 

 DELTODUS CINCTCLUS, St. J. and W 146 



Fig. 6 a. Mandibular posterior tooth, left ramus, view from above, extremity restored 

 in outline; 6 b, do., from inner margin, transverse profile; 6 c. do., ante- 

 ro-lateral border, longitudinal profile. Warsaw beds; Madison county, 

 111. Prof. Worthen. 



Fig. 7 a. b. c. Similar views of a maxillary posterior tooth, left ramus. Barrett's Sta- 

 tion. Mo. Prof. Worthen. 

 DELTODUS TRILOBUS. St. J. and W 148 



Fig. 8 a. Mandibular median tooth, left ramus, view from above; 8 b., do., from inner 

 margin; 8 c. do., from outer margin, extremity broken away; 8 d. do., 

 longitudinal profile from antero-lateral border; 8 e. do., from postero- 

 lateral border; 8/. transverse section, showing prominent definition of 

 the anterior and posterior lobes. Warsaw limestone; Jersey connty. 

 111. Prof. Worthen. 

 DELTODUS OCCIDENTALIS (Leidy, sp.) 150 



Fig. 9 a. Maxillary posterior tootb, left ramus, from above. St. Louis limestone; 

 Monroe county. 111. Prof. Worthen. 



Fig. 10 a. Mandibular median'tooth, right ramus, from above, outer extremity broken 

 away; 10 b. do., from antero-lateral border; 10 c. do., postero-lateral 

 border; 10 tf.do., transverse section. Warsaw beds; Warsaw, 111. Prof. 

 Worthen. 

 DELTODUS LATIOB. St. J. and W 145 



Fig. 11 a. Medium-size tooth of the mandibular posterior form, right ramus, from 

 above. Keokuk; Hamilton, 111. Prof. Worthen. 



Fia. 12 a. A smaller individual of the same form; same locality. 



Fig. 13 a. b. c. DELTODOS CINOULATUS, N. and W 



(Geol. Surv. of 111., Vol. II. p. 99, PI. IX. flg. 6.) 



13 a. Maxillary posterior tooth, left ramus. from above; 13 b. from ante- 

 ro-lateral border; 13 c. outline from inner margin, transverse profile. 

 Chester limestone; Chester, 111. Prof. Worthen. 



DELTCDUSINTEBMEDIUS. St. J. and W 155 



Fig. 14 a. Maxillary posterior tootb, left ramus, from above; 14 b. do., transvere profile 

 from inner margin; 14 c. do., from outer margin; 14 d. do., from antero- 

 lateral border, longitudinal profile; 14 e, do., from postero-lateral border; 



14 /. do., showing inferior surface. St. Louis formation; Pella, Iowa. 

 Mr. St. John. 



Fig. 15 a. b. c. d. Similar views of a small example of the same form, right ramus, 

 showing a marked undulated coronal surface. St. Louis; Columbia, 

 Monroe county, 111. Prof. Worthen. 



