NORTH-CAROLINA GEOLOGICAL SURVEY. 



FIG. 208. 



P. ARATUS. (Fig. 208.) 



This is the smallest species of this genus be 

 longing to the shell marl. It is also one of the 

 most common. P. passus and P. quinqueruga- 

 tus are also common in certain localities. 



LEDA ACUTA. (Fig. 20SA.) 



FlG - 208A - Shell small, thick, inflated pos 



teriorly; margin acute or beaked, 

 slightly open ; anterior margin, 

 short rounded ; surface concen 

 trically striated. This fossil re 

 sembles nucula, but it is not pearly in the interior, and its ab 

 dominal margin is smooth. 



oute, 



NUCULA PROXIES ab uU 208B.) 



Shell small, d^ ra ( mooth, interior pearly ; 

 anterior margin short ; posterior side elongat 

 ed, obtuse ; margin crenate. 1ST. limatula is 

 more common in the marl beds of this State 

 than the N. proxima ; miocene. 



FIG. 208s. 



FAMILY CHAMACIDAE. 



The shell is thick, inequavalve, with sub-spiral beaks, hinge 

 teeth 1 2, muscular impression one, and large ; reticulated 

 palleal line simple. 



CIIAMA. 



The shell is attached to other bodies by its left umbo : 

 hinge-tooth of the free valve thick, curved, and received be 

 tween the teeth of the other valve. 



CHAMA ARCINELLA. (Fig. 209.) 



Shell thick, or orbicular-cordate squamose ; the radiating 

 ribs spinose, strong, tubular or folded ; intervening space 

 coarsely punctate and rugose. Common in the marl bed at 

 Klizabethtown, Bladen county. 



