206 THE FORAMINIFERA 



specimen of this variety, in which the slender spines 

 are still attached. (Plate 11, fig. G.) 



Genus Orbulijia, D'Orbigny. 



Test having the external form of a single spherical 

 chamber with two sorts of perforations, large and 

 small ; pelagic specimens often with a thin shell-wall 

 and radiating spines. 



Example. — 0. imiversa, D'Orbigny, 'Foram. Cuba,' 

 1830, p. 3, pi. i. fig. 1. 



This consists of a spherical chamber, sometimes 

 modified by showdng a bilobation or protuberance on 

 one side. Usually the interior, especially in the thin- 

 shelled pelagic forms, contains a small Glohigerina- 

 like series of chambers fastened to one side of the test. 

 It has been considered by some Ehizopodists that this 

 genus is only of quasi-generic value, and that it is a 

 reproductive stage of the typical Glohigerina. It is 

 a very common form in all surface dredgings, and the 

 tests often constitute a large proportion of the Glohi- 

 gerina oozes accumulating at the present time. 

 ( ? Camhrian.) Lias to Becent. (Plate 11, fig. I.) 



Genus Hastigerina , Wyville Thomson. 



Test regularly nautiloid, involute ; shell- wall thin, 

 finely perforated ; armed with long serrate spines. 

 Aperture a large crescentiform opening at the base of 

 the last chamber. Essentially pelagic. Recent. 



Example. — H.jyelagica, D'Orbigny sp. {Nonionina), 

 'Foram. Amer. Merid.' 1839, p. 27, pi. iii. figs. 13, 

 14. 



