TBUNCATELLA. Panama Shells. 218 



317. Truncatella Bairdiana, vNov<,8p.::n^ .,•: 



Shell cylindric : of a rich amber color : with rather small 

 crowded ribs, which are obsolete behind the labrum, less pro- 

 minent on the convexity of the whorls, well developed ante- 

 riorly, in number about twenty -four on the penult whorl: apex 

 acute, truncate with the loss of four whorls : spire with the out- 

 lines slightly curvilinear; whorls nearly four after truncation, 

 convex, with a well impressed suture : aperture ovate, slightly 

 effuse above: labrum advanced along the middle, reflected, 

 double: labium with a thick deposit, continuous with the 

 labrum. 



Mean divergence about 22°, being considerably less in the 

 lower whorls and more above ; length after truncation, .21 inch ; 

 breadth .075 inch ; length of spire .15 inch. , 



This species must resemble T. scalariformis Eeeve from the 

 island of Annaa; but that shell is figured with five whorls after 

 truncation, in color it is described as " luteola," and the labrum 

 is said to be sharp and simple. ^ 



Station. — Under a heap of stones at the high-water mj^rk of 

 spring tides. 



Hahitat. — Panama ; 0. B. A. I 



400 specimens were collected at the bottom of the, sea wall of 

 Panama. 



One specimen has come to. maturity without, the loss, of. the 

 apex, which, however, is white. and, cretaceous, f^om partial 



decay. 



We dedicate this species to Professor S. F.Baird, iwhose 

 name is so weU known to Herpetologists. ,-, . i ., ,-i.> , . 



318. Truncatella (II) dubiosa. Nov. sp. 



Shell ovate conic : translucent, deep yellowish brown : thin, 

 smooth, and shining: apex subacute: spire with the outlines 

 moderately curvilinear: whorls six, convex, with a well 



JULY, IB52. 64 Ann. Lto. Nat. Hist. 



