THE FAMILY LAGENID^E 191 



Ak. Wiss. AVien,' vol. xlvi. pt. i. 1862, p. 91, pi. xii. 

 figs, la, h. 



This genus was particularly abundant in Cretaceous 

 seas ; the above example is a typical one from the 

 Gault, and it also extends its range into the Chalk. 

 (Plate 10, fig. K.) 



Genus Hhahdogoniiiin, Eeuss. 



Test straight or slightly curved, angular or sub- 

 carinate, usually three- or four-sided. Lias to Becent. 



Example. — B. tricarinatmii, D'Orbigny sp. (Vagi- 

 nulina), 'Ann. Sci. Nat.' vol. vii. 1826, p. 258, No. 4; 

 ' Modele,' No. 4. 



The typical examples of the above species are 

 confined to Tertiary strata, where it has a wide 

 distribution. A variety (acuta iKjiiIuni, Reuss) has 

 been described from Lower Cretaceous beds of 

 Aptian age in Germany, and it also occurs in the 

 Gault of England. 



As a recent form it is common in the North 

 Atlantic from shallow water down to 1,360 fathoms ; 

 and it also occurs in the Mediterranean Sea and the 

 Pacific Ocean. Silvestri's specimen (see figure) 

 came from the Pliocene of Sienna. Tertiary to 

 Becent. (Plate 10, figs. L, /.) 



Genus Marginulina, D'Oebigny. 



Test elongate, curved; segments circular in 

 section ; aperture marginal. — Cambrian to Becent. 

 Example. — M. raricosta, D'Orbigny, ' Mem. Soc. 



