NORTH-CAROLINA GEOLOGICAL SURVEY. 



235 



FIGS. 61 & 62. 



SPHENODUS RECTIDENS. N. S. (FigS. 61 & 62.) 



Tooth very long ; comparatively slender ; both 

 faces convex ; internal more so than the external ; 

 becoming narrower towards the edges ; the base 

 in some of the teeth trenchant, then nearly par 

 allel two-thirds the length ; enamel rather thick 

 grooved on the inside, and cracked longitudinally 

 on both, with a texture coarser than in the 

 lamna ; root unknown. Figure 62, transverse 

 section. Green sand of North-Carolina. 



GENUS IIEMirRISTIS. 



Apex simple and smooth ; margins of the tooth 

 denticulated to a point near the apex. 



FIG. 63. 



HEMIPRISTIS SERRA. AGASS. (Fig. 63.) 



The H. serra is characterized by 

 teeth which are serrated to a point near 

 the apex, where the serratures cease, 

 and the margins are left smooth. 



HEMIPRISTIS CRENULATUS. N. S. 



Form similar to the H. serra ; sides 

 convex, long at base, and rather thick ; 

 enamel smooth, and marked with only 



a few cracks ; edges at base faintly crenate ; entire towards 



the apex. 



GENUS OXYRHINA. 



Tooth flat, broad, oblique, lanceolate and smooth, widening 

 at base rapidly ; root thin and nearly straight, and destitute 

 of spreading branches or forks. 



