24:2 SYSTEMATIC PALEOXTOLOGY 



closely resembles. Our Eocene forms have more chambers than the 

 CretaceoiTS specimens of New Jersey which show nine. The mouth 

 ojjening is also more prolonged and the sutures somewhat depressed be- 

 tween the chambers. 



This species is found in many places in the Cretaceous of Xew Jersey, 

 Eancocas (Bagg), Septaria Clays near Berlin (Bornemann), ISTorth Ger- 

 man Hils and Grault (Eeuss), and elsewhere. 



We must regard the species as an intermediate variety between the 

 elongate compressed Cristellaria crepidula, and the symmetrical lenticu- 

 lar Cristellaria rotulata. The form occurs in the North Atlantic and in 

 the South Pacific at depths of less than 500 fathoms (Brady). 



Occurrence. — Aquia Foemation. 1 mile northeast of Piscataway, 

 Upper Marlboro. 



Collection. — Maryland Geological Survey. 



Ceistellaria eotulata (Lamarck). 

 Plate LXIII, Fig. 5. 



Lenticulites rotulata Lamarck, 1804, Annales du Museum, vol. v, p. 188, No. 3. — 



Tableau Eneycl. et Meth., pi. cccclxvi, fig. 5. 

 Cristellaria rotulata d'Orbigny, 1840, Mem. Soc. geol. France, vol. iv, p. 26, pi. ii, 



tigs. 1.5-18. 

 Cristellaria rotulata Parker and Jones, 186.5, Phil. Trans., vol. civ, p. 345, pi. xiii, 



tig. 19. 



Description.- — Test involute, biconvex, smooth; peripheral margin 

 sharp, non-carinate; chambers numerous, eight or nine in final convolu- 

 tion; septa gracefully curved, visible externally as fine lines; aperture 

 elliptical radiate. Diameter, 1-2 mm. 



While the above species is abundant in the Cretaceous of New Jersey 

 and in the Eancocas reaching a large size for this type, it and all other 

 C ristellariae are exceedingly scarce in the overlying Eocene. The type 

 secured from Mason Springs is very large and thick-shelled. Since 

 such a form would he readily preserved it is difficult to account for the 

 lack of the species elsewhere while so many much more delicate Foram- 

 inifera abound. 



It is doubtful if any Foraminifera is more widely distributed or more 

 abundant either living or in fossil state than CristelJarin rotulata. 



