RHIZOPODA—FORAMINIFERA. 8 3 
there exist a number of recent species which are visible to the naked 
eye. Some species of Orbitolites are nearly half an inch in diameter, 
and the discs of Cycloclypeus, dredged living off the coast of Borneo, 
are more than two inches in diameter; and among fossil forms of 
large dimensions may be mentioned Parkeria (Carpenter), from the 
Upper Greensand near Cambridge, which sometimes reaches to three 
inches in length ; and Loftwsia (Brady), from Persia, specimens of 
which have been met with three inches long and one inch and a half 
in diameter. Here also allusion may be made to the gigantic Eozoon 
canadense, lately discovered in the Paleozoic rocks of Canada. 
After these remarks, we may venture to give some idea of the 
structure and classification of beings whose part in the work of 
creation has in former times been so considerable. 
The existing Foraminifera are by no means equally distributed in 
every ocean. Some genera belong to warm countries, others to 
temperate and cold climates. They are much more numerous, 
however, and much more varied in their forms, in warm than in 
cold climates. 
And first as to their structure. We find this to consist of a soft 
sarcodous material of the same nature as that met with among the 
Lobosa, and in addition they possess a calcareous skeleton. There is 
even less approach than with the Amcoebe to either shape, size, or 
number in their pseudopodial extensions—these often present them- 
selves as marvellously attenuated threads, requiring very high powers 
indeed of the microscope to discern them. They coalesce both readily 
and completely with one another, while along their margins streams of 
granules may be seen continuously passing. There is an apparent 
absence either of “nucleus” or of a “contractile vesicle,” which 
were occasionally present among the Lobosa. By far the larger 
number are enclosed in calcareous shells, which are perforated with 
minute pore-like openings for the escape of the pseudopods, and 
from the presence of which the familiar name of Foraminifera has 
been given to the class.) These pseudopodial extensions present in 
this group a peculiar reticulated character, whence the name of 
Reticulosa, given to it by Dr. Carpenter, whose monograph on the 
group is a monument of patient industry and research. 
We have already said that the shells of these minute creatures 
vary much in form. They are generally many-chambered, each 
chamber communicating by pores in its walls. Alcide d’Orbigny, 
to whom—until Carpenter’s “Introduction to the Study of the Fora- 
minifera” was published—we owed almost all that was known of the 
class, has distributed it into six families, making the form of the shell 
G2 
