56 HENRY B. BRADY, 
specimens they figure (op. cit. pl. 15, figs. 13—17) to the 
species now described rather than to B. elegantissima. 
B. subcylindrica, nov.,.is another form belonging to the 
same group as B subteres. The test is elongate, sub- 
cylindrical (not tapering), the two ends equally rounded, 
and the surface but little excavated at the sutures. 
The segments are few, and their spiral arrangement is 
very obscure: the aperture takes the form of a narrow, 
nearly erect slit, near the base of the final segment. 
Length, => inch (0°5 mm.). 
B. Williamsoniana, nov.—Test elongate, cylindrical, more 
or less sinuate in contour, circular in transverse sec- 
tion ; composed of a spiral band of long narrow, nearly 
erect segments. Inferior extremity slightly tapering and 
rounded, superior obliquely truncate. Surface traversed 
from end to end by a series of somewhat sinuate and 
diagonal parallel coste, which entirely obscure the 
internal structure. Aperture simple, situate in a depres- 
sion at the centre of the oblique superior face, bordered 
by radiating lines. Length, ,!; inch (0°64 mm.) or less. 
Borivina, d’Orbigny. 
Excepting the genus Lagena, there is no group of hyaline 
Foraminifera the knowledge of the varietal modifications of 
which has received larger accessions from the study of the 
“ Challenger ” material, than that comprising the aberrant 
forms of Bulimina, included under the subgeneric terms 
Virgulina and Bolivina. Both diverge from the typical plan 
of structure in their tendency to become more or less regu- 
larly biserial, instead of spiral, in the arrangement of their 
chambers, whilst they usually retain the characteristic 
Bulimine aperture. It is impossible to separate these two 
subgenera one from another by any well-defined or perma- 
nent peculiarity; all that can be said to distinguish them 
is that Virgulina is more Bulimine and less Textula- 
rian in the disposition of its segments, and that Bolivia is 
more Textularian and less Bulimine. Whilst, therefore, it 
is comparatively easy to associate Vergulina with its type, 
Bolivina often only betrays its affinity by the aperture, which 
is either comma-shaped, twisted, toothed, unsymmetrically 
oval, or of some other form within the range of variation to 
be found in Bulimina itself. In the varieties of Vérgu- 
lina we find all the links connecting Bolivia with the 
typical Bulimina. Two or three undescribed species of 
Virgulina way be omitted from the present notice, as de- 
scriptions in few words would be scarcely intelligible with- 
