208 THE FOEAMINIFERA 



polished surface. The perforations of the test are 

 very minute ; Dr. Brady gives as their approximate 

 diameter -j^loo of an inch (O'OOl mm.) It first 

 makes its appearance as a fossil in the Chalk-marl, 

 and continues through many formations of succeed- 

 ing age to the present time. It is now a widely dis- 

 tributed form in deep-sea deposits. (Plate 11, figs. 

 K, k) 



Genus S'pluBvoidina, D'Oebigny. 



Segments few, coiled so as to form a nearly 

 globular shell ; aperture arched ; sometimes partially 

 closed with a valvular tongue. Cretaceous to Recent. 



Example. — >S'. hulloides, D'Orbigny, ' iVnn. Sci. 

 Nat.' vol. vii. 1826, p. 267, No. 1 ; ' Modele,' No. 65. 



The test of this species is nearly spherical, but 

 somewhat flattened at the umbilical axis. The 

 chambers to a certain extent embrace the earlier part 

 of the shell, so that only the last three or four cham- 

 bers — practically the last convolution — are visible. 



In the fossil state >S'. hullo ides first makes its 

 appearance in the Gault of Folkestone. It has also 

 been found in the Chalk of Meudon, France, and of 

 the Island of Riigen, and it is a well-known and widely 

 distributed species in the faunas of the Tertiary beds 

 of Europe generally. At the present time it is found 

 from the coast of Norway to the Southern and Indian 

 Oceans, and at almost every depth where Foramini- 

 fera are obtained. It has not yet been ascertained 

 whether this species is pelagic. Cretaceous to Becent. 

 (Plate 11, fig. L.) 



