100 THE NAUTILUS. 



CHAMA MONROENSIS n. sp. PI. IV, fig. 15. 



Shell of medium size, strongly rugosely plicated, lamellar. Upper 

 valve with 6-8 leaves turned up to nearly a vertical at their ventral 

 edges, each leaf covered with radial raised lines running in couples. 

 Upper valve slightly convex, lower valve convex and inequilateral. 



Resembles somewhat O. corticosa Con., but is smaller and more 

 profusely ornamented. One lower valve has twelve leaves or corru- 

 gations. The upper valve is shown in the figure natural size. 



Locality : The 0. sellseformis bed, at White's Marl bed, Monroe 

 Co., Alabama. 



PECTEN (PSEUDAMUSIUM) SUBMINUTUS n. sp. PI. IV, figs. 16, 17. 



Shell minute, thin, surface smooth, not polished, valves rather flat, 

 ears small, subequal in the right valve and unequal in the left. Fine 

 rugose stria? on the ears of the right valve, vertical to the hinge line 

 but not reaching it, but they run down over the submargin. One 

 ear in the left valve with five or six radiating ribs, the other smooth ; 

 interior smooth, the cardinal margin cross striated. 



Alt. 3 mm., lat. 3 mm. of the largest specimen. 



Localities : Red Bluff, Miss., Jackson, Miss. 



This little shell is evidently adult. It is probably found at Vicks- 

 burg also. It is not rare, closely resembles Pecten Guppyi Dall in 

 form, but is smaller. 



VERTICORDIA DALLIANA n. sp. PI. IV, fig. 18. 



6 



Shell small, rather flat, surface ornamented with sharp curved ribs, 

 in the present specimen thirteen in number, nine on the anterior, 

 then a concave space as if one rib was missing, then two more ribs 

 about the middle of the shell, then a wide concave space and then 

 two more ribs, the last one almost at the margin. Ribs serrating the 

 ventral margin. Cardinal tooth strong, erect ; lateral tooth long and 

 curved. 



Breadth 2^ mm., height from beak to base 2 mm. 



Only one valve found ; it is about the same size as V. eocense 

 Langdon. The muscular scars are slightly impressed. Pallial line 

 not perceptible. 



VERTICORDIA SOTOENSIS n. sp. PI. IV, figs. 19-21. 



Shell small, strongly ribbed with twelve ribs, then a blank space, 

 then two ribs near the margin, beaks blunt and rounded, ventral 



