THE FORAMINIFERA 



and 2|-3f whorls of chambers arranged in a spiral form the 

 earlier part of the test. The later, straight part is much longer 

 than in the megalospheric form, and in both forms the biserial 

 arrangement may give place to a uniserial one at the end. 



The characters of other genera of this family are indicated in 

 the table of classification, and some of them are represented in 

 Fig. 44, C-E, and Fig. 54. 



ORDER Chilostomellidea. 

 I am not aware of any record of dimorphism in this order. 



ORDER Lagenidea. 



Schlumberger has found representatives of both generations 

 in Nodosaria (Dentalina) guttifera and Nodosaria hispida, the megalo- 

 spheric forms beginning in a large initial chamber (Fig. 45, A), 

 larger than that which succeeds it, and having only five or six 



Flo. 45. 



Megalospheric forms of A, Nodosaria hispida, d'Orb. B, Nodosaria (Dentalina) communis, 

 d'Orb. C, Frondicularia alata, d'Orb. (After Brady, 3.) 



chambers in all ; the microspheric having a larger number of 

 chambers, and tapering gradually to a fine point at which the 

 little microsphere is situated. In such tests the phenomenon of 

 dimorphism is presented in the simplest possible form. 



Fornasini (15) has shown that Frondicularia (Fig. 45, C) is 

 dimorphic. 



The monothalamous Lagenidae often present a great resem- 

 blance to the single chambers of Nodosaria, but the nature of the 

 relation between the two groups is obscure. Neumayr derives the 

 former from the latter by degeneration ; Rhumbler, by the falling 



