ON THE GENUS POLYMORPHINA. : 233 
longer, more cylindrical subtype than. P. fusiformis, with a larger number of chambers 
and less oblique setting on; indeed it resembles more a much. outdrawn specimen of P.. 
problema than any other variety. 
We have given references to a number of Ehrenberg’s figures, which may, we think, 
properly be placed under this species. Proroporus Crete and Pr. Siculus. are somewhat 
shorter than our figure ; and Bigenerina acanthopora is armed with a terminal muero; but 
we cannot regard these as variations of sufficient importance to merit specific separation. 
Some of M. Terquem's Liassic Polymorphine seem also to belong to P. Thouini.. His P. 
pupiformis represents a very mixed set of specimens, mostly ranging between P. Thouini 
and P. nodosaria, with some others that we should hesitate to place in the same genus. 
Distribution.— Accepting M. Terquem’s figures representing Liassic specimens as 
belonging, in part at least, to this species, it is one of the earliest in its appearance. We 
have notes of its occurrence in the Eocene beds of the Paris Basin, in various Pliocene 
clays of North Italy, and in the Crag of our Eastern Counties. 
In the living state it is a rare shell. A sample of Lévant dredgings, obtained by Capt. 
Spratt at a depth of 90 fathoms, off Syra, contained a few specimens, the only recent ones 
on record. : 
POLYMORPHINA NODOSARIA, Reuss... (Plate XL. figs. 18, a, b.) 
? Vaginulina paradoza, Ehrenberg, 1854, Mikrogeologie, pl. 26. fig. 26. 
Polymorphina subnodosa, Reuss, 1860; Sitzungs. Akad. Wissensch. vol. xlii. p. 362, pl. 2. fig. 15. 
P. nodosaria, Reuss, 1863, Sitzungs. Akad. Wissensch. vol. xlviii. p. 58, pl. 7. fig. 85. 
P. quadrata (in part), Terquem, 1864, 4"* Mém. Foram.. Lias, p. 296, pl. 12. figs. 27 &e. 
Dimorphina nodosaria, Jones, Parker, and Brady, 1866, Monogr. Crag Foram. pl. 1. figs. 55-58. 
Polymorphina nodosaria, Reuss, 1866, Denkschr. mathem.-natur. Cl. k, Akad. Wissensch. vol. xxv. p. 155. 
Characters.—Shell elongate, cylindrical, somewhat tapering, irregular, composed of 
from 4 to 8 chambers. Chambers oblique, inflated, alternating. Sutures constricted. 
Orifice central, radiate.. Surface smooth. Length 35 to ys inch. 
It may be questioned whether the uniserial Polymorphine typified by P. nodosaria 
belong more properly to the principal division of the group or to the subgenus Dimor- 
phina. On the whole, it seems most convenient to confine the term Dimorphina to those 
varieties which begin growth on a biserial or triserial plan, and, after a certain number of 
segments have been formed, lapse into a single rank. In the present species, the mode 
of growth is uniserial from the commencement, or very nearly so; and its chief departure 
from the characters of the simpler type it otherwise resembles is in the alternating 
obliquity of the septal lines. Thus, while the genus Vodosaria has horizontal ‘sutures 
connecting the chambers, and Dentalina has oblique septa, all slanting in one direction, 
Polymorphina nodosaria has oblique septa the direction of which is reversed with each 
succeeding segment. "The general outline of the shell is somewhat irregular, from the 
different convexity of the segments; but its central axis is straight. | 
© The Polymorphina subnodosa of Prof. Reuss does not represent so good a type as that 
more recently described under the name which we have adopted; and Ehrenberg's figure: 
is unreliable, for reasons already explained. lg 
