216 THE FOEAMINIFEEA 



Genus PateUina, Williamson. 



Test conical, consisting of an external layer of 

 spirally arranged or annular chambers divided into 

 chamberlets ; the interior of the cone filled either 

 with hyaline shell-substance or by an aggregation of 

 compressed chambers. Loiver Cretaceous to Becent. 



It seems advisable to restrict this genus to the 

 hyaline forms, and to retain the generic terms 

 Orhitolina and Gomilites for the subarenaceous 

 fossils, which are nevertheless morphologically similar 

 to the above genus. 



Example. — P. corrur/ritn, Williamson, ' Eecent 

 Foram. Gt. Britain,' 1858, p. 46, pi. iii. figs. 86-89. 



It is interesting to note that this identical 

 species, held to be a degenerate form of the sub- 

 arenaceous type Orbitolina, was existing in the seas 

 of the Lower Cretaceous period at the same time as 

 the larger morphological types, as evidenced by its 

 occurrence in the prolific fauna of the Bargate stone 

 series in Surrey. This interesting little species 

 is distinguished from the larger fossil forms by its 

 clear hyaline shell-structure. Like the preceding 

 genus, H-pirillina, it seems most at home in fairly 

 shallow water. Aptian to Becent. (Plate 12, figs. 

 B, h.) 



Genus Cymiialojjoiri, Hagenow. 



Test more or less trochoid or complanate. 

 Segments of the trochoid forms spiral at the 

 apex, subsequently arranged concentrically round 



