834 
THE VOYAGE OF H.M.S. CHALLENGER. 
deposits. Mr. Brady remarks — Notwithstanding the wide geographical range of most 
of the recent species, a large number of new forms have been brought to light by the 
examination of the material collected by means of the dredge and tow-net ; and the 
results, taken in conjunction with those of the ‘Porcupine’ expedition of 1869, have 
furnished a basis for the systematic treatment of one extensive group of forms, previously 
but little understood, namely, those which construct composite or arenaceous tests in 
Fig. 303 . — Keramosphcera murrayi, Brady. 
«. Natural size ; b, magnified 25 diameters. 
e. Portion of a nearly central section of tlie same specimen, magnified 50 diameters. 
d. A smaller portion of the same, magnified 100 diameters, showing 1, 1, 1, 1, 1, the orifices communicating 
between the chamberlets of the successive layers ; 2, 2, 2, 2, lateral orifices communicating between 
the chamberlets of the same layer. 
place of the more usual calcareous skeleton. Much light has also been thrown on the 
range of morphological variation dependent upon local conditions ; and the extent of the 
area over which the collections were made has furnished data for a large reduction in the 
number of ‘species’ or of the varieties which amongst the Foraminifera are accepted 
as species. 
“ The relation of the pelagic Rhizopod-fauna of the ocean to that of the sea bottom, 
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