THE FAMILY NUMMULINID.F: 247- 



or clianibers ; thickened on either side by layers of 

 flattened chamberlets, more or less irregularly dis- 

 posed. Upper Cretaceous to Miocene. 



Example. — 0. (DiscocycUna) papijracea, Boub^e 

 sp., Giirnbel, ' Abhandl. m.-ph. CI. k. bayer. Ak. 

 Wiss.' vol. X. 1868 (1870), p. 690, pi. iii. figs. 3-12, 

 19-29. 



As a component of certain Tertiary limestones 

 this species is often of very great importance. It was 

 undoubtedly a foraminifer living in shallower water 

 than the related type Cycloclyp)eus, \yliich has a thinner 

 test ; and it formed extensive shell-banks, which 

 eventually became consolidated into beds of Orbi- 

 toidal limestone. This species is easily recognised 

 by its thickened central disc and expansive peri- 

 pheral flange. Eocene of Europe, Egypt, Persia, and 

 India. (Plate 14, figs. F, /, G, H, I.) 



The chief sub-generic types of Oi'bitoides are 

 based on the appearance of the chamberlets of the 

 median layer. The sub-genus DiscocycUna has the 

 chamberlets of a rectangular form, whilst the sub- 

 genus Lepidocyclina. (see Plate 14, fig. I) has them of 

 lozenge-shaped or spathulate form. The Discocyclines 

 are apparently restricted to Eocene beds, and the 

 Lepidocyclines occur in the Upper Cretaceous., the 

 Oligocene, and the Miocene. Other sub-generic 

 types are of little importance, such as AJdinocyclina, 

 Bhipiclocyclina, and Asterocyclina, their distinction 

 being based on external form alone. 



