SCAPHOPODA—SIPHONODENTALIIDJE. 



581 



Claibornian of Alabama, Louisiana and Mississippi. Abundant. 

 :. D. attenuatum Say. (Fig. 800, a.) Miocenic. 



Arcuate and rapidly tapering ; surface with 12 to 16 rounded 



Fig. 799. Dentalium thalloides. 

 (After Conrad.) 



Fig. 800. a, Dentalium attenuatum ; b, 

 c, D. caduloide. (Md. Surv. ) 



ridges separated by broader interspaces, and obsolete towards 

 narrow end. 



Chesapeakean of Maryland. 

 12. D. (Laevidentalium) caduloide Dall. (Fig. 800, b, c.) 



Miocenic. 



Smooth, regularly tapering and more gently curved than the 

 preceding. Section circular. 



Chesapeakean of Maryland. 



Family SIPHONODENTALIID^ Simroth. 



II. Cadulus Phil. 



Differs from Dentalium in being swollen near the middle and 

 tapering toward each end. Cretacic-Recent. 



13. C. turgidus Meyer. (Fig. 798, c.) Eocenic. 

 Rapidly increasing for about two thirds of length and then more 



rapidly decreasing. Section circular. 

 Midwayan of Alabama. 



14. C. abruptus M. & A. (Fig. 801, a.) Eocenic. 



