EORAMINIEERA FROM THE NORTH ATLANTIC AND ARCTIC OCEANS. 363 
Genus Uvigerina. 
Uvigerina pygmcea , D’Orbigny. Plate XIII. figs. 53-57 (Arctic) ; Plate XVII. 
figs. 65 a, 65 b (North Atlantic). 
Uvigerina makes up its shell normally of three series- of inflated chambers, alternating 
somewhat irregularly on an elongated spire. Its aperture is a very distinct and round 
passage, generally tubular (Ectosolenian) and lipped. The lip is sometimes faintly 
toothed, showing a relationship to the radiated mouth of the Polymorphina, Lagena , 
and JSfodosarina. To the last genus it is mostly related by its style of ornament, which, 
as a rule, consists of strong well-marked costas, parallel to the axis of the shell. In all 
large well-developed individuals, whether of typical or dimorphous growth, these costse 
are distinct and strong, just as obtains in the large Lagence and Nodosarince (Plate XVIII. 
figs. 16, 17). In weaker individuals the ribbing is less prominent and often becomes 
obsolete in the newer chambers (Plate XIII. figs. 56 & 57). Certain dimorphous forms 
are quite smooth (Plate XVIII. fig. 18). As in Nodosarice, some Uvigerinoe take on the 
aculeate or hispid ornamentation ; the ribs of each chamber either sending back one or 
more spines, or breaking up into prickles ; or the whole surface of the shell may become 
spinose and bristly. The hispid forms of Uvigerina are generally found at great depths 
(common at 1000 fathoms in the Tropical Atlantic, Indian Ocean, &c.), and are frequently 
angular in section, belonging to the variety U. angulosa, Williamson. In deep water 
also the large Uvigerinoe are frequently elegantly racemose, with a prickly surface ; the 
chambers are globular and distinct, and the tubular mouth much elongated: this botryoidal 
form is, as far as shape is concerned, the most deserving of the generic term “ Uvigerina" 
given originally to the really typical costate U. pygmoea, such as we have before us. 
Large Uvigerinoe of the typical form are especially abundant and well-grown in the 
southern and eastern parts of the Mediterranean, at from 100-300 fathoms : the home 
of Uvigerina seems to be in warm seas at this depth, but it is found also in shallower 
water (Coralline-zone), but is then of the small size. Feeble forms creep upwards, as it 
were, into shallow water, and downwards to great depths ; still the abyssal forms predo- 
minate over the littoral, the latter retaining the greatest resemblance to the typical 
■U.pygmcea; whilst the deep-water forms, whether angular or inflated, are prickly, the 
angular forms in shallow water are ribbed. 
In the elongated form, of feeble growth and faint striation (fig. 57), we may see a 
tendency to a biserial and even a uniserial growth ; the chambers ceasing to retain a 
definite triserial alternation ; and, becoming loose in their setting on, they present such 
a condition as leads ultimately to a uniserial row of chambers in the newer part of the 
shell. Such a dimorphous condition is clearly seen in certain figures, given by Soldani, 
of Italian Uvigerinoe , named U nodosa by D’Orbigny (Ann. Sc. Nat. vol. vii. p. 269) ; and 
we also possess similar forms both from the recent and the fossil deposit of the Medi- 
terranean area, Plate XVIII. fig. 15. These dimorphous specimens present a growth of 
either one, two, or three chambers in a straight line in the younger part of the shell 
