218 THE FOEAMINIFEEA 



Genus Discorbina,^ Paeker and Jones. 



Test free or adherent, Rotaliforni ; plano-convex 

 or trochoid, rarely complanate ; aperture an arched 

 slit, often protected by an umbilical Hap — the flaps 

 sometimes forming a whorl of subsidiary chambers. 

 Shell-texture somewhat coarsely porous. Lower 

 Cretaceous to Becent. 



Example. — D.patellifonjiis, Brady, ' Rep. " Chall." ' 

 vol. ix. 1884, p. 647, pi. Ixxxviii. fig. 3 a-c ; pi. 

 Ixxxix. fig. 1 a~c. 



This neatly built species is characteristic of the 

 genus. The lower surface of the test shows the 

 granulated surface or exogenous shell-layer, which 

 in some species presents the form of sutural thicken- 

 ings along the radial margins of the chambers, the 

 astral arrangement of which gave rise to the quasi- 

 generic group the Asterigerincp. 



D. j)ateUifonnis has occuTYed in the Pacific, and 

 from the shores of Ceylon, Madagascar, the Mauritius, 

 Malta, and South Australia. It is chiefly confined 

 to shallow water. Beceiit. (Plate 12, figs. E, e.) 



Genus Flaiiorbiiliiia, D'Oebigny. 



Test normally adherent ; compressed or com- 

 planate segments very numerous ; commencing 

 growth on a spiral plan, but subsequent^ becoming 

 more or less cyclical ; the lipped apertures of the 

 individual segments opening externally at the 

 periphery. Aberrant varieties often wild-growing 



