8 SHALLOW-WATER FORAMINIFERA OF TORTUGAS REGION. 
In Orbitolites duplex the pseudopodia were very straight and 
slender, extending out rapidly to a distance equal to the diameter 
of the test. They are put out in groups of 3 to 12 from each of the 
marginal apertures of the test. There is very little coalescing in 
the pseudopodia of Orbitolites duplex in contrast with Iridia diaphana, 
where anastomosing is of usual occurrence. In Orbitolites, pseudo- 
podia an inch in length were several times noticed. One specimen 
of Orbitolites was broken in being taken from a leaf of Posidonia and 
the two halves of the test were separated, leaving a clear space 
entirely across, after which pseudopodia were sent out from the 
entire periphery. In Haliphysema advena the pseudopodia were very 
slender and showed little tendency to join. 
One important observation was that in the case of Jridia diaphana 
taken from Posidonia leaves and placed in Petri dishes over night. 
In the morning some of these were found to have left their test 
empty and were moving about as naked masses of protoplasm with 
a free and comparatively rapid movement. That the animal may 
leave the test and pass some time without one is very significant 
from the standpoint of the method of growth. Growth of the test 
in those species which have a single chamber has often been a subject 
of speculation. If the test can be abandoned at will and another 
secreted or made by collecting more material in the case of those 
which have agglutinated tests, this difficulty is solved, and we may 
also understand how various sedentary species can collect various 
materials which are not common for their tests. Given free move- 
ment and a power of discrimination, which seems to be a character- 
istic of certain species, it is not difficult to explain how such tests 
are made of one sort of building-material—spicules, mica flakes, 
ambulacral plates of brittle-stars, etc. The occurrence of specimens 
of Iridia on Posidonia some inches above the bottom, while its 
test is made of material from the bottom is also explained. The 
material could easily be carried up to this elevation while ingested 
in the moving mass of protoplasm, and then sent out to the sur- 
face when the animal settled down to build the test. 
TABLE 1. 
Minutes. | Seconds. || Minutes. | Seconds. || Minutes. | Seconds. |} Minutes. | Seconds. 

The movement of the whole animal without the test was observed 
and measured in Jridia diaphana, and with the test in Discorbis 
