ON THE GENUS POLYMORPHINA. 281 
tinguishes it from the commoner modifications. Setting this aside, we have in the Poly- 
morphina lingua (Woodcut f) and P. obscura of Roemer * two of the lanceolate varieties, 
having a transverse diameter equal to about one-third of the length, and showing the 
characteristic arrangement of the chambers. Our own specimens from the Crag yield 
many intermediates, two of which are represented in Woodcuts g and 4, whilst D'Orbigny's 
figure (+) exhibits the extreme form. P. subrhombica (j) appears to be only a few- 
chambered and somewhat stouter modification, possessing otherwise the same general 
features. 
Polymorphina complanata is very closely connected with P. compressa and P. regularis ; 
but the thickened centre and obscures eptation of the one, and the unequal and irre- 
gular disposition of the segments of the other, and its depressed sutures, will in general 
prevent their being confused with the more regularly built specimens of the form -under 
consideration. 
Distribution. — Well-marked Textularian Polymorphine seem only to be known as 
Tertiary fossils. The Miocene beds of the Vienna Basin were the source of D'Orbigny's 
specimens; and the various Tertiary formations of North and North-western Germany, 
and the Crag of the east of England, have supplied those of later observers. 
POLYMORPHINA ELEGANTISSIMA, Parker and Jones. (Plate XL. figs. 15, a-c.) 
Polymorphina elegantissima, Parker and Jones, 1864, Phil. Trans. vol. clv. Table x. p. 438. 
Characters.—Shell oblong or oval, thin, complanate, composed of a number of long, 
areuate, erect chambers, arranged in two unequal series. The final segment of each 
series large, and embracing those previously formed, the arrangement being reversed on 
the two sides of the shell. Chambers but slightly convex, occasionally having an ill- 
defined border or blunt carina. Surface smooth. Length ys inch. 
This beautiful variety received bare mention in the Appendix to the Memoir on North- 
Atlantic and Arctic Foraminifera above referred to, and is now first described and figured. 
It differs from other modifications of the type in the peculiar obliquity of its segments, 
which are arranged in two alternating series, but in such a way that on each face of the 
shell one of the series is completely invested by the overlap of its large terminal chamber. 
The series of segments which is exposed on one face of the shell is covered on the other, 
and vice versé. Thus from whichever side it is viewed, it presents four or five arcuate or 
semicircular chambers, with their ends embraced by the outspread terminal segment of 
the opposite series. 
Distribution.—We have specimens of Polymorphina elegantissima from shell-sand col- 
lected near Melbourne, Australia, and from soundings in Storm Bay, Tasmania, the latter 
forwarded to us by the late Dr. Greville, of Edinburgh. Though it has not been met with 
* Herr Roemer's drawings are, unfortunately, too small and indistinct to be of much service—a i tance the more 
to be regretted as they were amongst the earliest illustrations of Tertiary Foraminifera. In many cases the want of 
definite character in the figures has precluded the adoption of names that might otherwise have taken precedence of 
those in use. Prof. Reuss, in subsequent papers relating to geological formations of similar age, has reproduced some 
of the drawings on a larger scale, thereby restoring their value. Our remarks on P. T and P. obscura are founded 
- on the later figures rather than on those of the original plate. 
