VEETEBRATES. 79 



tooth, coronal enamel forming a narrow belt rounded to the basal 

 border, which was probably of shallow depth ; postero-lateral border 

 converging toward point of inrollment at an angle of about 35 with 

 the opposite border, and similarly denned by the rounded enamel 

 fold, which in both borders shows indistinct traces of minute crenu- 

 lation, basal rim in either border not known; inner margin making 

 a broad sigmoidal curvature, broadly arched round the base of the 

 coronal prominence from the subacute posterior angle, with a moder- 

 ate concavity in papsing to the obtuse anterior angle, in worn speci- 

 mens inbeveled inferiorly. Coronal prominence occupying three- 

 fourths of the entire area of the crown surface, moderately elevated 

 and broadly arched transverely, the broader slope regularly rising 

 from the postero-lateral border into the nearly median low crest and 

 slightly more steeply sloped into the shallow depressed belt occupy- 

 ing the anterior portion of the surface ; the coronal surface is 

 traversed by strong, more or less regularly spaced undulations 

 parallel with the inner margin, the intervening sulci occupied by the 

 irregularly elongated orifices of the medullary tubes which elsewhere 

 appear as minute circular pits, spaced by three times their own 

 diameter, surrounded by low rims with faint stellate radiations ; in 

 worn surfaces the transverse undulations become obsolete, though 

 the position of the sulci is still plainly discernible by the parallel 

 bands of coarse pores. Greatest lateral diameter of a medium size 

 tooth 30 m. m., length along antero-lateral border to point of inroll- 

 ment about 15 m. m. 



The above described form which was discovered by Dr. Hambach, 

 is represented by three individuals, all belonging to the right ramus 

 of the upper jaw, one only presenting a nearly entire tooth. This 

 is sufficiently perfect to permit satisfactory comparison with con- 

 generic forms and the discrimination of its specific peculiarities. 

 Intimately allied to the earlier occurring species, it is at the same 

 time distinguishable from that described from the Warsaw horizon 

 of Indiana, Tceniodus rcgidaris, by its relatively narrower propor- 

 tions and more oblique outline; "it differs from T. fasciatus, of the 

 Keokuk formation, as also the form provisionally identified with 

 that species from the Warsaw beds above Alton, both in its greater 

 obliquity and transverse diameter. At the same time it bears a 

 general, resemblance to the Belgian species T. contortus, De Kon., 

 which latter, however, is relatively longer, the enamel fold of the 

 lateral borders much more strongly developed, and in the distinct 

 depression of the posterior slope of the crown surface. 



