THE FAMILY EOTALIID^ 219 



and irregular, sometimes acervuline. Shell-wall 

 coarsely porous. 



The granulate discoidal forms lately described 

 from Cebu, Philippines, by Schlumberger, under the 

 name of Liiiderina, may belong to this type of 

 Foraminifera. Tertiary to Becent. 



Example. — P. larvata, Parker and Jones, 'Ann. 

 and Mag. Nat. Hist.' ser. 3, vol. v. 1860, p. 21)4 ; 

 'Phil. Trans.' vol. civ. 1865, p. 379, pi. xix. 

 figs. 3 rt, h. 



This parasitic form is usually of a regularly 

 discoidal shape, and is characterised by the acervu- 

 line centre, with the marginal ring of apertural 

 chambers. It is often abundant in sands of coral 

 areas. Becent. (Plate 12, fig. P.) 



Genus TruncatiiUna, D'Oebigny. 



Test free or adherent, Kotaliform ; the inferior 

 face generally more convex than the superior. Shell- 

 wall coarsely porous ; surface sometimes tuberculated, 

 especially in old shells. Aperture a curved slit at 

 or near the superior margin of the inner edge of the 

 final segment, sometimes with a phialine neck and 

 lip. In one instance the aperture is compound, 

 peripherical (epistomine), and normal. Carhoniferous 

 tu Beccjit. 



Example. — T. luhatida, Walker and Jacob sp. 

 {Nautilus), Adams's ' Essays,' Kanmacher's ed., 1798, 

 p. 642, pL xiv. fig. 36. 



Of the plano-convex types of Truiicatuliiia this is 

 perhaps the most characteristic form, and it is 



