THE FAMILY MILIOLIDiE 99 



Genus Corn7is2)ira, Schultze. 



Consists of a planospiral tube, which is un- 

 divided. 



This genus is isomorphous with certain species of 

 the arenaceous genus Animodiscus and the byahne 

 genus SjnriUina. 



Coiiiusjyira has been doubtfully recorded from the 

 Carbo-Pennian of Tasmania. The recorded occur- 

 rences of the genus from Jurassic and Cretaceous 

 rocks are not satisfactory, for the specimens gene- 

 rally prove to be Aiiujiodisci on minute examination. 

 The genus is common, how^ever, throughout Tertiarij 

 fossiliferous strata to recent times. 



Example. — C. mvolveiis, Eeuss, ' Sitz. k. Ak. Wiss. 

 Wien,' vol. xlviii. (Abth. 1), 1868 (1864), p. 39, pi. i. 

 Hg. ± 



This species is distinguished by the embracing 

 character of the whorls as they rest successively on 

 each in turn, as well as in the roundness of the tube. 

 In this latter feature it differs from C. foliacea, which 

 has a thin flattened shell. It is usually a shallow- 

 water form, but is sometimes found at considerable 

 depths. Tertiarij to Becent. (Plate 4, fig. A.) 



Genus PeneropUs, Montfokt. 



Chambers undivided ; arrangement either plano- 

 spiral throughout or spiral only at the commence- 

 ment, subsequently becoming rectilinear or cyclical. 

 Tertiarij to Becei/t. 



Examples. — P. arietinus, Batsch sp. {Nautilus — 



u 1> 



