REPORT ON THE FORAMINTFERA. 
219 
tion. Tlie superficial cliamberlets of the same zone have no immediate connection with 
each other, nor is there any direct connection between the superficial cliamberlets of 
the adjacent annuli. The communication is maintained indirectly by means of the 
annular galleries, in a manner analogous to that which has been observed in the simpler 
types, each chamberlet having two pores or passages, one at each end, opening respec- 
tively into the annular canals of its own zone and the previous zone. And, as there are 
two superficial layers of chamberlets in the complex type, so there are two series of 
annular canals. 
The “ intermediate stratum ” is composed of columnar or cylindrical chamberlets, 
which, making some allowance for irregularities, correspond in number and arrangement 
with those of the superficial layers. These columnar sub-segments terminate above and 
below in the annular gallery of the zone to which they belong, and they each communi- 
cate by stolon iferons passages with the contiguous chamberlets of the preceding and 
succeeding annuli. The radial stoloniferous passages of the cylindrical segments of the 
outermost zone form the marginal pores which are seen on the exterior. From what has 
been stated it will be seen that the complete intercommunication of the various parts of 
the cavitary system is attained, firstly, by the opening of the chamberlets both of the 
superficial layers and of the intermediate stratum into the annular canals ; and secondly, 
by the direct stoloniferous passages between the chamberlets of the concentric zones of 
the intermediate stratum. 
In the very young condition the shell is occasionally adherent, growing attached to 
the fronds of algse or other similar bodies, as shown in PI. XVI. figs. 2, 3 ; but more fre- 
quently it is free from the commencement, and specimens in the very earliest stage, 
consisting of nothing more than the “nucleus” (fig. 1), are often found amongst the sand 
of localities in which the species abounds. 
The shells of this species are subject to irregularities of growth which take place in 
many different ways. Perhaps the commonest sort of monstrosity is that illustrated by 
some of the figures in PI. XVII., in which a portion of a second disk is projected from one 
of the lateral faces of the test (fig. 1). Occasionally portions of more than one supple- 
mentary or out-growing disk are found, as in figs. 3, 4, and 5 ; and other forms of 
irregularity, dependent on uneven or arrested growth, are not unfrequent. 
Orbitolites complccnata has probably a wider geographical distribution than any of its 
congeners. It is found in the shallow margins of tropical and sub-tropical seas, but it is 
more generally diffused over the eastern than the western hemisphere. It is common on 
the shores of the Pacific, from the Loo-choo Islands and the Sandwich Islands on the 
north, to the coast of Tasmania on the south, attaining its best development on the coral- 
reefs of the Fiji and the Friendly Islands, and it is almost equally abundant in the Indian 
Ocean. There appears to be some doubt as to its presence in the Red Sea and the 
Mediterranean, at any rate its reported occurrence requires confirmation. It has been 
