FORAMINIFERA. 



109 



is still extremely variable in form, but it consists typically of 

 a series of chambers wound round an axis, in such a manner 



Fig. IS. Types of Foraininifera. a, Cornuspira foliacea; b, (Juinqiwloculina seminuluw ; 

 c, Peneroplis pertusus ; d, Lihwla aggluthwns; e, Trochammina pusillus ; f, Lagena sulcata; g, 

 Nodosaria radicula ; li, Marginulina ruphanus; i, Frondicukiria Archiaciana; j, Polymorphina 

 lactea; fc, Globigerina bulloides ; I, Textularia sagittula ; m, Cassidulina Icevigata ; n, Bu'iminti 

 r,uchlana;o, Rotalia Beccarii ; p, Truncatulina lobatula ; r, Arduediscus Karreri ; s, Polystom- 

 ella crispa; t, Amphtetegina I^ssoni. All the figures are greatly enlarged, the real diameters 

 varying from 1-100 to 1-10 inch. (H. B. Brady.) 



that each embraces half the entire circumference. This genus 

 dates from the Jurassic (Lias), and is well represented in 



