MARYLAND GEOLOGICAL SURVEY 46?" 



the superior surface is trochoid Avliile the inferior remains nearly flat 

 and again the lower side becomes the arched and the superior the de- 

 pressed area. In the normal Rotaliform arrangement of chambers the 

 whole of the segments appear upon the superior surface and only those 

 of the last volution on the lower aspect. Prof. Brady states that while 

 the umbilicus is sometimes depressed more usually there is an exogenous 

 deposit of shell substance over it. The aperture is normally a curved 

 Assure on the inferior face of the final segment. 



The present distribution of the genus is in tropical and temperate 

 ;^ones, and it is typically developed in shallow waters of tropical seas. 

 Its first geological occurrence is in the Gault of England. 



EoTALiA BECCARii (Liune). 

 Plate CXXXI, Figs. 12, 13. 



Nautilus heccarii Linne, 1767, Syst. Nat., 12th ed., p. 1163 ; 1788, Syst. Nat., 13th 

 (Gmeliu's) edit., p. 3370, No. 4. 



Description. — Test trochoid, shell wall finely porous and the form 

 built into a compact low nearly circular spire; peripheral margin lobu- 

 lated, obtusely rounded, chambers numerous, ten to forty, somewhat in- 

 flated, about ten in the final convolution. Septal lines depressed below 

 and nearly straight; curved al:)Ove and the whole number of chambers 

 visible on the superior side. Convolutions about three, inferior surface 

 thickened, and often beaded with exogenous granules at the umbilicus. 

 Aperture a notched subdi\aded opening or a series of pores at the inner 

 margin of the ultimate chamber. This foraminifer rare in the Miocene 

 becomes plentiful in the Pleistocene of Cornfield Harbor, Md. Its fos- 

 sil form begins with the middle Tertiary. 



Occurrence. — St. Maey's Formation. Cove Point. Choptank 

 Formation. Jones Wharf. 



Collection. — Maryland Geological Survey. 



EoTALiA BECCARII VAR. BRCECKHiANA Karrer. 

 Plate CXXXI, Fig. 14. 



Hotalia brceckhiana Karrer, 1878, Drasche's Geo], d. Insel Luzon, p. 98, pi. v, tig. 

 36. 



Description. — This variety of the Rotalia heccarii is only a thickened 



form of the type species and differs from the latter in the more convex 



