244 SYSTEMATIC PALEONTOLOGY 



Description. — " Shell depressed, small, smooth, glossy, and naked 

 above, with from one to three sharp carina3, the upper one small, often 

 wanting; volutions 3-4, with a depression or subcanal near the suture; 

 umbilicus large, open, coarsely striated within; peritreme sharp, slightly 

 interrupted by the body whorl. 



'^ Diameter, ^ of an inch; aliiiude, -i the diameter." Wood, 1848. 



This form, Avhich is very rare at the single Maryland locality Avhere it 

 has been found, has a wide distribution in the Miocene and Pliocene of 

 the Atlantic coast of the United States, the Pliocene of Europe, and is 

 living on both shores of the Atlantic. 



Height, 1 mm. ; diameter, 2 mm. 



Occurrence. — St. Mary's Formation. St. Mary's Kiver. 



Collections. — Wagner Free Institute of Science, Cornell University, 

 U. S. ISTational Museum. 



Family CALYPTR/EID/E. 



Genus CRUCIBULUM Schunincher. 



Crucibulum costatum (Say). 

 Plate LVIII, Figs. 7a, 7b. 



Uulyptnea coxtata Say, 1820, Ainer. Jour. Sci., vol. ii, p. 40. (Reprint, 1800, Bull. 



Amer. Pal., No. .5.) 

 Dispotiva costadi Say, IS'J4, Jour. Acad. Nat. Sci. Phila., vol. iv, 1st ser. , ji. KW. 



(In part.) 

 Not Dispotwa coHtata Conrad and others. 

 DispoUia grandis Conrad, 1842, Proc. Nat. Inst., Bull, ii, p. IS.t. Not of Say. 



Description. — " Oval, convex, with numerous slightly elevated, equal 

 equidistant eostae, and crowded obtuse, concentric lines, which are regu- 

 larly undulated by the costge; apex mamillated inclining to one side; 

 inner valve patelliform, dilated, attached by one side to the side of the 

 shell, acutely angulated at the anterior junction, and rounded at the pos- 

 terior junction, and rapidly tapering to an acute tip, which corresponds 

 with the inner apex of the shell." Say, 1820. 



The original locality of this species as given by Say is Upper Marlboro 

 and the fossils which he mentioned as associated with it are all Calvert 

 forms. Undoubtedly the material came from one of the numerous Mio- 

 cene outliers in the vicinity of Upper Marlboro. Both the original lo- 



