EOEAMINIEEEA 1'EOM THE NOETH ATLANTIC AND AECTIC OCEANS. 345 
in C. Calcar , Linn., sp. When the keel is wanting, we have Cristellaria rotulata , Lamarck. 
There are no specific differences in their features. 
Fig. 18 shows an irregularity of growth, and a disposition to depart from the nauti- 
loid form towards the simpler varieties in which the greater distinction of the chambers 
is preserved. Several angles around the periphery of the shells are sometimes formed, 
rendering their outline polygonal. Other variations of growth are not uncommon ; the 
polymorphism of these simple organisms being very great. 
Plate XVI. fig. 5 (North Atlantic). 
A smallish nautiloid Cristellaria with moderately developed keel, such as fig. 17 of 
Plate XIII., but differing in the non-essential features of greater obliquity of chambers 
and more distinct umbilical knob. 
Rare at 78 fathoms, lat. 51° 59', long. 11°, North Atlantic. 
Cristellaria rotulata , Lamarck, sp. Plate XIII. fig. 19 (Arctic). 
Here the keel is nearly obsolete. This carina is generally all that is left to us in 
these nautiloid forms of the longitudinal striae or costae that so frequently ornament the 
subspecies of the large Nodosarina group. Occasionally, however, the lateral faces of 
the shell bear raised costae crossing the chambers, nearly at right angles, as in the ribbed 
Nodosarice and Marginulince (typical), and in many Vaginulince , Flabellince, and Fron- 
dicularice. 
The Cristellarice represented by figs. 17-19 occur, common and large, in the Arctic 
Circle, Nordland, on a muddy bottom at 160 fathoms. 
These recent northern specimens are, as regards size, equal to such as we find in those 
rich Cristellarian deposits, the Chalk and Chalk-marl. Like the rest of this group, how- 
ever, the largest of this form are found in the Subapennine Tertiaries, the Vienna 
Basin, and in the Tertiary beds of Jamaica and San Domingo. Exactly similar speci- 
mens of Cristellarice abound in the rich shelly bottom, at 50 fathoms, in the Port of 
Orotava, in the Canaries ( Bobulina Canariensis , D’Orb. For. Canar. p.127, pi. 3. figs. 3, 4); 
and forms nearly as large are not at all uncommon in the Mediterranean, especially in 
mud at from 50 to 100 fathoms. In the Adriatic, however, this, with other Cristellarice , 
is found of similar size in shallow water. 
Of small size, these are found on our own coasts and throughout all seas. They are 
fossil in very many Secondary and Tertiary deposits, but of rather small size in the 
older strata ; nevertheless in these latter beds they are exceedingly abundant and charac- 
teristic, not being mixed so much with species of other families of Foraminifera that 
have come in at a later epoch. 
Genus Lagena. 
For full descriptions, general and special, of this genus we refer to Professor Wil- 
liamson’s Memoir on Lag ence, Annals Nat. Hist. 2 ser. vol. i. 1848; and his ‘Mono- 
