250 MESSRS. BRADY, PARKER, AND JONES 
two forms he separates specifically, correspond very nearly ; but .D. tuberosa is said to be 
recent, and to have its alternating segments more largely developed than D. nodosaria, 
which he regarded as essentially a ‚fossil species. The relative development of the two 
portions of the shell, in point of fact, varies with each individual specimen ; and the mere 
question of time, we repeat, cannot rightly be admitted as an element affecting zoological 
characters. 
Distribution.—Dimorphina tuberosa is rare. It occurs as a fossil in the Tertiary 
deposits of Italy and Spain, of the Vienna Basin, and the East of England. Mediterra- 
nean soundings from depths not exceeding one hundred fathoms occasionally bring to 
light living specimens. | 
DIMORPHINA OBLIQUA, D'Orbigny. (Plate XLII. figs. 40, a—c.) 
Dimorphina obliqua, D'Orbigny, 1846, For. Foss. Vien. p. 220, pl. 12. figs. 18-20. 
Characters.—Shell elongate, arcuate. Anterior and posterior extremities acuminate. 
Chambers oblique, convex. Aperture excentric. Surface smooth. Length + inch. 
The uniserial chambers of D. obliqua, as described by D'Orbigny, are in a curved line, 
and oblique in their setting-on, simulating the characters of Dentalina rather than those 
of the straight Nodosarine. The primary alternating segments are few, small, and incon- 
spicuous. We have never met with specimens having precisely the aspect shown in the 
“ Vienna ” plates, the nearest approach being the elongate Polymorphine with two, or 
sometimes even three, oblique chambers, succeeding each other in one line, occasionally 
to be met with in shallow-water dredgings ; and in these examples the uniserial segments 
are not developed with the regularity which marks M. D'Orbigny's figures. Judging 
from analogy, the existence of such a form might be anticipated; and if the biserial (or 
spiral) chambers are habitually as small and inconspicuous as they are represented in the 
drawing, it is not surprising that they have been overlooked by other observers. It is 
more than possible that two specimens figured by M. Terquem as Bigenerina dentalini- 
Sormis (Sixième Mémoire sur les Foraminifères du Lias, pl. 22. figs. 29, 30) are Dimor- 
phine ; and if so, they differ from D. obliqua chiefly in their extreme length and tenuity ; 
but the drawing is too obscure to permit exact diagnosis. 
Our figures are copied from the original ones (For. Foss. Vien. pl. xii.), and somewhat 
enlarged for the sake of greater distinctness. 
Distribution.—The sole habitat given by D'Orbigny is ** Baden res Vienna), not 
common,” his specimens being, of course, Miocene fossils. 
DIMORPHINA COMPACTA, spec. nov. (Plate XLII. fig. 41.) 
Dimorphina tuberosa (in part), Jones, Parker, & Brady, 1866, Monogr. Crag Foram., App. I. & II. pl. 1. 
fig. 66. ; 
Characters. —Shell elongate, subcylindrical, arcuate, compactly built; anterior 
extremity obtuse or truncate; posterior rounded. Margin even; septa marked only by 
faint lines. Later segments set on obliquely. Length #5 inch. 
This variety furnishes another instance of the close parallelism that exists between the 
