2123 . MESSRS. BRADY, PARKER, AND JONES 
the Shetland area, it is met with at every point on the shores of the British Islands, 
and again in the British Channel and the Bay of Biscay. Its occurrence in the Me- 
diterranean strikingly follows the variations of depth: the table before alluded to, which 
embodies the results of a large series of observations*, shows its entire absence at 170, 
250, 306, 500, 1100, 1620, and 1700 fathoms, whilst at 90 fathoms (off Syra) the at- 
tenuated variety is noted as “rare;” and the common forms by degrees come in, in 
the shallower water of the Gulf of Spezzia, off Leghorn, and off Crete; and, again, 
specimens of the genus have been noticed by many observers in the lesser depths of 
the Levant. 
Polymorphine are found in the Red Sea, on the coast of China, amongst the Australian 
eoral-reefs, in the sea-harbours of Tasmania, on the eastern shores of the American con- 
tinent, in the West-Indian archipelago, and amongst the Canary Islands. 
In all dredgings taken from mid-ocean the absence of the genus is conspicuous ; in the 
deep Atlantic, whether in the northern, tropical, or southern portions, it is unknown; and 
there is no record of its occurrence at great depths in the Indian Ocean. 
The distribution of the genus in time, geologically speaking, is similarly extensive. 
If we aecept the aggregations of green sand-grains figured by Prof. Ehrenberg under 
the names Polymorphina avia and P. abavia as glauconite casts of the chambers of 
Foraminifera (and, notwithstanding some doubt that has been thrown upon their organic 
origin, we must admit the extreme resemblance his two figures bear to some specimens 
of Polymorphina compressa), the first appearance of the genus must be placed back as far 
as the Lower Silurian sands of the neighbourhood of St. Petersburg. It has not, how- 
ever, been noted in rocks of Palæozoic age by any other author. 
In the Secondary period, specimens of Polymorphina, usually of the few-chambered, 
weaker forms, become gradually more frequent. In the Upper Trias of Derbyshire 
(Jones and Parker), the Raibl beds of southern Germany (Gümbel), and in the various 
Liassie marls of England and continental Europe examples of the genus are found, though 
rarely. It again makes its appearance in the Oxford and Kimmeridge clays (Middle and 
Upper Jurassie respectively), in the Portland beds, in the Gault, and the Chalk; and 
during the Tertiary period it occurs in abundance wherever conditions of depth and sea- 
bottom have been favourable. "Though apparently wanting in the London Clay, speci- 
mens of the genus are to be found in some of the Lower Eocene beds of England ; but 
in the Lower Tertiaries of the Paris district, in the Miocene strata of Bordeaux, of the 
Vienna Basin, and of Lower Bavaria, it exists in wonderful variety. In the later Tertiary 
beds of the Mediterranean area there is a curious discrepancy to be observed: the Italian 
Pliocene marls contain a fair representation of the genus, whilst beds of corresponding 
age on the Spanish coast (Malaga) yield no Polymorphine whatever: and the same 
absenee is to be observed in a peculiar marl-bed of Miocene or late Eocene age at 
Baljik, on the Black Sea. In the Southern Hemisphere, such of the Tertiary clays as 
have been examined, e. y. those of New Zealand and South Australia, show a large 
number of specimens pertaining to the type. In one particular bed of the “Crag " of 
our own Eastern Counties (at Sutton, near Colchester) the size and abundance of the 
y Quarterly Journal of the Geological Society, vol. xvi. p. 302. 
