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Cincinnati Society of Natural History. 



Ctenoboi,bina loculata, n. sp. 

 Plate VIII, Figs. 13 and 14. 



Size: Length, 1.00 mm ; hight, without flange, 0.54 mm., 

 with flange, 0.60 mm. 



The lobation in this small species is singularly like that of 

 the Ordovician C. crassa and C. subcrassa, and the latter is 

 simulated even to the possession of a small node in the upper 

 and inner corner of the posterior lobe. The valves in C. 

 locnlata, however, are relatively longer and more equal-ended, 

 while the construction of the flange is quite different. In- 

 stead of the thick, yet simple type of flange, pertaining to 

 those species, we have here a strongly undulated plate sup- 

 ported by walls or pillars which divide the space intervening 

 between the flange and the ventral edge into four subequal 

 cavities. The undulations and extent of the flange remind 

 of the preceding species, C. granosa, but in that form there 

 are no cavities beneath, while the lobes are appreciably dif- 

 ferent, and the surface granulose instead of smooth. 



Formation and Locality. — Rather rare in Safford's Maury 

 shales of the Lower Carboniferous system, at Mt. Pleasant, 

 Tennessee. 



KlRKBYA CYMBULA, n. Sp. 



Plate VIII, Figs. 15-18. 



Size: Left valve: length, 0.97 mm.; hight, 0.50 mm.; 

 thickness, 0.20 mm. Right valve: length, 1.10 mm.; hight, 

 0.54 mm. 



Carapace oblong subquadrate, the hinge line long, straight 

 or slightly convex, the ventral edge straight or slightly 

 sinuate in its central portion, the anterior margin obliquely 

 truncate and most prominent at the antero-cardinal angle ; 

 the posterior margin more rounded, though forming an angle 

 where it joins the hinge line. Sides of valves enclosed by a 

 thin raised rim, within which the surface is almost flat and 

 traversed by more or less irregular longitudinal ribs, ten or 

 eleven in number, separated by narrow furrows, of which 

 each contains a row of small punctse. Situated a little behind 

 and more above the middle of the valve is a well-defined 

 oval pit. 



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