Wright — Foraminifera of Down and Antrim. 321 



Lagena guadrata (pi. 1, figs. 27, 28), two distinct species. Fig. 27 is an oblong 

 form of L. laevigata, and this variety is known by Williamson's name ; fig. 28 

 is L. bicarinata. Both species are often met with around our coast. 



lagena marginata var. insequilateralis, Nov. (PI. xxvi. fig. 10, a,b,c) 

 This curious variety of L. marginata has one side strongly convex, the 

 other side being flattened, or slightly concave ; aperture at the flattened side. 

 Rare. Common in a fossil state in the Estuarine Clay, Lima vady Junction. 



Splrillina margaritifera, Williamson. (PI. xxvi., fig. 12, a — b.) 



Spirillina margaritifera, Williamson, 1858, Rec. For. Gr. Br. p. 9, pi. vii. 



figs. 2—4. 

 The following is Professor Williamson's description of this species, the 

 type in brackets being additions of mine : — " Shell consisting of numerous 

 narrow, somewhat convex, (?) convolutions— the outer one smooth, the inner 

 one obscured by numerous projecting tubercles, arranged in one or two series ; 

 In some parts these are most conspicuous along the centre of the convolution ; 

 in others along the spiral septal line " [peripheral edge square] . ' ' Texture 

 hyaline, diam., -gV." 



Williamson (loc. cit.~) describes the convolutions of this species as convex. 

 A somewhat similar foi-m, differing only in the convolutions being square, has 

 been found at several localities around our coast, and so closely does his 

 description and illustration agree with these specimens, that I have no hesita- 

 tion in considering them the same. The specimens recorded as Spirillina 

 tuberculata, both by Siddall, in " Memoir on the Foraminifera of the Estuary 

 of the Dee," and by Balkwill and myself, in " Foraminifera of Dublin Bay 

 and Irish Sea," should, I feel satisfied, be referred to S. margaritifera, and S. 

 tuberculata should be no longer included among the British species. S. mar- 

 garitifera differs from <S. tuberculata in the outer convolutions being smooth, 

 the peripheral edge square, and the tubercules being stronger, and not so 

 numerous. 



/K 



