REPORT ON THE FORAMINIFERA. 
691 
No. 10, which represents a compressed, regular, neatly constructed, Rotaline shell, with 
subcarinate, slightly lobulated periphery. It is composed of about two convolutions, the 
outermost consisting of six segments ; the sutures are limb are on the superior side, more 
or less depressed on the inferior. Good examples have often a diameter exceeding -^th 
inch (P27 mm.). 
Commencing with the comparatively thin, outspread, Pulvinulina menardii, the 
closely allied species Pulvinulina canariensis, Pulvinulma crassa , and Pulvinulina 
micheliniana , together with some minor varieties, constitute a complete gradational series, 
the shells of which, by successive modifications of the shape of the chambers and their 
setting-on, assume, to a greater or less degree, the biconvex, plano-convex, or subconical 
contour. The subordinate “ specific ” groups cannot be separated by any sharp lines of 
demarcation, but the central characters of each are well marked, and there is seldom any 
practical difficulty in assigning specimens to one or other of the recognised forms. 
Pulvinulina menardii is more abundant than any of its congeners as a pelagic 
organism. It was taken in surface-gatherings, during the Challenger cruise, at nine 
points in the North Atlantic, at seven in the South Atlantic, at six in the South Pacific, 
aud at seven in the North Pacific. 
Its distribution, within certain latitudes, is world-wide. The record furnished by 
bottom-dredgings includes altogether not less than one hundred localities, scattered over 
the North and South Atlantic, the North and South Pacific, the Indian Ocean, the 
Southern Ocean, the Mediterranean, and the Red Sea ; the depth ranging from shallow 
water down to 2750 fathoms, but being seldom less than 200 fathoms. Its northern limit, 
so far as at present known, is about lat. 55° 11' N. in the North Atlantic; its southern 
boundary about lat. 51° 36' S. in the South Atlantic. In somewhat higher latitudes, 
north and south, it is replaced by Pulvinulina canariensis. 
As a fossil it has been identified as far back as the Chalk-marl of Kent (Jones and 
Parker) ; and the white Cretaceous limestones of Sicily (Ehrenberg). It occurs in the 
Eocene of the Bavarian Alps (Gfimbel), in the Miocene and Pliocene of Southern Italy 
(Seguenza) ; in a Pliocene deposit in the Nicobar Islands (Schwager) ; and in a white 
limestone, probably of similar or still later geological age in the New Britain group 
(Brady). 
Pulvinulina menardii, var. jimbriata, nov. (PL CIII. fig. 3, a. b.). 
This is a subordinate modification, dependent on the exuberant growth of the shell. 
The normal subcarinate or limbate peripheral border of the spire is increased by the 
further deposit of shell-substance, so as to form a thick, serrate, or fringe-like keel. The 
test is seldom so large as that of the type. 
Free-swimming specimens of the fimbriate variety have been obtained in company 
