REPORT OF THE DIRECTOR I918 163 



like Pleurostomella from which genus it is sharply defined by its 

 septal arrangement and different primordial chambers. Bulimina 

 is often triserial, but in its unsymmetrical serial extension it resembles 

 Virgulina. Moreover, in living forms Virgulina is a delicate, hyaline, 

 thin-walled, calcareous foraminiferan like Bolivina, while Bulimina 

 is often larger, thicker shelled, and more roughly constructed than 

 the former. All Bulimina types, however, show wide variation in 

 their arrangement of chambers, which is always more or less complex 

 and overlapping. This is true of Virgulina, which changes from 

 biserial to uniserial growth and shows the most widely divergent 

 irregularity in the symmetry of its chambers. In Bolivina there 

 are usually a large number of segments and they are of uniform size 

 as they unfold. In Virgulina, however, these do not match but 

 overlap irregularly and unevenly and are much more strongly 

 arched when shown in cross sections. 



Bolivina and Bulimina are both known from early Trias deposits; 

 but Virgulina has, as far as we are aware, never been recorded in 

 Lower Paleozoic strata. It has been recorded from the Cretaceous 

 chalk, becomes more frequent in the Tertiary, and exists today in 

 worldwide oceans without regard to depth or latitude. We recognize 

 several species of this unique genus in the Bonaventure chert and 

 the following illustrations, chiefly from slide 2, indicate the general 

 construction of the species which in a measure are so closely related 

 that they are to be regarded rather as subspecies than widely 

 divergent forms. 



Virgulina schreibersiana Czjzek 



Plate 2, figures 7, 8 



Bulimina presli var. (Virgulina) schreibersii, Parker & 

 Jones, 1865, Phil. Trans., 155: 375, pi. xv, fig. 18, pi. xvii, figs. 72, 73 



Virgulina schreibersiana Go 2s, 1894, K. Sv. Vet. Akad. Handl., 

 V. 25, no. 9, p. 48, pi. ix, figs. 459; 461-72 



It is with some difficulty that this species is separated from the 

 closely related form, V. squamosa d'Orbigny, when viewed 

 in transverse section. It is however, somewhat more rounded at 

 the primordial end, consists of fewer chambers and the segments 

 are almost uniserial above with more pronounced depressions at the 

 sutures. There are but five segments in one of the forms identified, 

 while seven or eight occur inV. squamosa on the same slide. 

 The form described by Jones, 1895 (Pal. Soc, 49:166, pi. vi, fig. 20) 

 under the varietal name obesa, according to our opinion belongs here. 



