78 PALAEONTOLOGY OF ILLINOIS. 



margin, coronal enamel apparently forming a narrow fold, basal 

 border not preserved; inner margin broadly arched from the 

 subacute posterior angle round the base of the coronal prominence, 

 thence with a slight concavity on the way to the obtuse anterior 

 angle, worn specimens inbeveled below. Two-thirds or more of the 

 coronal surface is occupied by the posterior lobe or prominence, 

 which is gently and regularly arched transversely, the anterior 

 slope descending into the very shallow concavity of the anterior 

 portion of the crown, which is abruptly truncated at the articular 

 border; surface marked by irregularly spaced transverse undula- 

 tions, which are nearly obsolete in worn specimens, and producing 

 a banded appearance conforming in outline to the inner margin; 

 the punctae are small, moderately closely arranged and uniform, 

 save in the axes of the transverse furrows where they often present 

 irregular elongate orifices. The surface of the dense inferior layer 

 is smooth or irregularly striated longitudinally. The tooth is very 

 thick and massive beneath the coronal prominence, whence its sub- 

 stance gradually diminishes in thickness towards the lateral 

 borders. Greatest breadth of tooth across the inner margin 45 

 m m, length of antero-lateral border to point of enrollment proba- 

 bly nearly 22 m m, or in the neighborhood of two-thirds that of the 

 postero-lateral border. 



The description is founded upon a unique example purporting to 

 have been derived from a locality on 'the Warsaw limestone near 

 Bedford, Indiana. The tooth is unmistakably congeneric with the 

 form noticed under the name Tceniodus fasciatus, but representing a 

 somewhat larger and more entire individual. It is, however, 

 specifically distinguishable from the latter by the proportionately 

 greater breath and transversely more regularly arched coronal 

 prominence, which does not exhibit the sudden deflection in the 

 course of the transverse undulations noticeable in the above cited 

 species. 



Geological position and locality : Warsaw limestone, near Bedford, 

 Lawrence County, Indiana. 



T^ENIODUS OBLIQUUS, St. J. and W. 



PI. XIII, Fig. 10. 



Maxillary posterior ( ?) teeth of medium size, obliquely trapezoidal 

 in outline, somewhat strongly arched from within outwards. Antero- 

 lateral border obliquely produced outward and forward at> an angle 

 of about 20 with a right line connecting the inner angles of the 



