Fig 



26. 







26 



a 



Fi B . 



27. 







27 



a. 



Fij:. 



28. 







28 



a. 



Plate VIII. — C out in u e d . 



PAGE. 



Fig 24. Agassizodus corrugatus, N. and "W 323 



24 a. View of the posterior face of a medium sized tooth of one of tbe median rows, 



showing the greater portion of the crown, the outline of the base restored ; 

 b, anterior face; c, crown as seen from above, the apes, broken away, and 

 extremities restored in outline ; d, profile section. Upper Coal Heas., near 

 Mauhattan, Kansas. 



Fig. 2"). Peript-ectrodus Warkeni, St. J. and W 325 



25 a. Yiew of a nearly perfect tooth, from above, showing the coronal cusps aud the 



beveled lateral edges; fr, profile view, showing the strong inrollment of the 

 anterior extremity of the mature teeth ; c, view of the posterior tVice, show- 

 ing the deep, massive basal portion, beneath which appears the iniolled 

 anterior portion of the crown. Burhugton creek, Iowa. Upper Burlington. 



Periplectrodus compressus, St. J. audW 326 



Yiew from above, enlarged two diameteis, showing the lateral compression of 

 the tooth; 26 b, protile view, showing the slight inrollment; 26 c, posterior 

 face. Alton, Illinois ; St. Louis limestone. 



Periplectrodus expansls, St. J. and AY 327 



Yiew from above of a small specimen exhibiting a pair of coronal cusps, enlarged 

 one diameter.- 27 b. profile view ; 27 c, posterior face, showing tbe lateral ex- 

 pansion of the basal portion. Chester, Illinois ; Chester limestone. 



STEMAIATODUS SYMMETRICUS, St. J. and TV 333 



Yiew from above, showing the coronal cusps, and callosities at the anterior ex- 

 tremity of tbe tooth, enlarged; 2S b, protile view; 2ti c, posterior view, 

 showing the inferior surface of base, fore-shortened. Bufh'ngton creek, 

 Iowa; U. .Burlington. 



Fig. 29. STEMMATODU6 CHEIKIFORMIS, St. J. and W 330 



29 a. Yiew from above, showing the flattened anterior border, and irregular disposi- 



tion of the cusps; *M b, profile view; 29 c, inferior surface, enlaiged. 

 Buffington creek, Iowa; U. Burlington. 



30 a Yiew from above of a nearly perfect tooth, showing the striation of the posterior 



cusps, and the minute abraded cusps in the angle of the anterior extremity, 

 enlarged six diameters ; 30 b, view from below, showing inferior basal sur- 

 face, and relative position of the posterior cusps, one of the large exterior 

 ones broken away and restored in outline. Buffington creek, Iowa. 



Fig. 31. Stemmatodi's bifurcatcs, St. J. and W 330 



31 o. Yiew from above, enlarged one diameter, showing the postero-lateral prolonga- 



tions, and the relatively brief or arrested median row of cusps: 31 6, profile 

 view ; 31 c. view showing the inferior basal region, evidently, more or less 

 abraded. Buffington creek, Iowa; U. Burlington. 



Fig. 32. Stemmatodl-s bicristatus, St. J. and \Y 331 



32 a. Tooth as seen from above, a minute and apparently perfect specimen, enlarged ; 



32 b, profile view, showing the downward produced anterior or terminal ex- 

 tremity ; 32 c, view from below, showii g the excavated basal surface. 

 Buffington creek, Iowa; U. BurLngtoii. 



33 a. Superior surface of a large specimen, having firmly attached to the narrow ante- 



rior extremity a pair of apparently similar but much worn dental crests, be- 

 tween which the larger body is wedged; 33 6, profile view, the outline of 

 base restored in outhue; 33c, view from below, the base much worn, and 

 showing tbe anteroinferior borders of the pair of anteiior teeth. Buffington 

 creek, Iowa. 



Fig. 34. S'lKMMATOUL'S simplex, St. J. ant! W 332 



34 a. Profile view of a large single CTested toolh. a portion of the external layer 



broken away in the posterior half, revealing tbe sutures defining the individ- 

 ual cusps in the body, or dentinal portion of the tooth. Burlington, Iowa ; 

 U. Burlington. 



Fij: 35. Stemmatoi>i> ihci;istaii>, St. J. aud \Y 331 



35 a, b,c. Superior, profile, and inferior views of a medium size specimen, showing towards 



the anterior extTemity only a single row of small appressed cusps, while to- 

 wards the opposite extremity a double row of alternating etisps are seen. 

 Buffington creek, Iowa; U.Burlington. 



Fig. 36. Stemmatolu's simplex, St. J. and YV 332 



36 a. Yiew from above of a large, single crested tooth, which exhibits the anomalous 



features of a bud or bifurcation abruptly arising from one of the lateral sur- 

 faces nearly midway between the extremities, and which consists of three 

 strong cusps, apparently firmly soldered to the main body of the tooth. 

 Buffington creek, Iowa: U. Burlington. 



37 a. b. Yiews from above and in profile of a symmetrical single crested tooth, the base, 



which is worn, restored in outline. Buffington creek, luwa. 



Fig. 38. Stemmatodus compactub. St. J. and W 334 



3E a. Yiew o*' upper surface of small tooth, bearing a median row of large cusps, with 



faint indicaiious of rudimentary lateral "cusps ; 38 6, profile view, base par- 

 tiallv restored in outline. Chester. Illinois; Chester limestone. 



