ROTALIIDAE-——_TRETOM PHALUS. 43 
the bottom specimens may thus be accounted for can not be stated 
with any degree of certainty. It seems possible that the enlarged 
“‘balloon-chamber”’ is developed from a bottom-living form, as many 
species adapted to a pelagic life develop a more or less inflated 
final chamber with large pores. These evidently allow free passage 
of the protoplasm, which, being extended and containing gases, 
floats the test without difficulty. Sir John Murray, while on the 
Challenger, observed living specimens of Tretomphalus bulloides, filled 
with ‘‘flagelli spores(?)’’ which were then noted and have since 
been referred to by various authors. These had small bodies at 
one side which took stain more freely than the general mass. 
In the tow-nets in the work at the Tortugas I frequently took 
Tretomphalus bulloides at the surface, especially in the open waters 
off Loggerhead Key. Some of these had the ‘‘float-chamber”’ con- 
taining a large air (?) bubble about half the diameter of the test. 
Murray also noted this in his fresh material. In these pelagic 
specimens there were often swarms of what were apparently zoo- 
spores, capable of rapid movement, but showing no flagelle or cilia, 
so far as could be observed. It was suggested by Earland that 
these might be discharged and on rupture of the ‘‘balloon-chamber’”’ 
the upper rotaliform portion might settle down to the bottom again 
and live on as Discorbis or as Cymbalopora poeyt. My own observa- 
tions would tend to disprove this, for in all the specimens observed 
no protoplasmic mass was left in the rotaliform portion, this also 
being filled with zoospores, as was shown by crushing this part 
when none were observed in the “float-chamber.’’ On crushing 
such specimens, numbers of zoospores came from the smaller cham- 
Fics. 2, 3.—Tretomphalus bulloides 
(d'Orbigny). 
‘3 2. Dorsal side, showing change in size 
of pores in progressive chambers. 
8. Outline of ventral side after removal 
of finalchamber. — 

bers of the rotaliform portion, but no undifferentiated protoplasm. 
Murray has already noted that none of his pelagic specimens con- 
tained the ordinary form of protoplasm seen in the other For- 
aminifera. These zoospores are so minute (0.001 to 0.0015 mm.) 
that they could easily pass through the pores of the spherical 
“balloon-chamber”’ and to it from any part of the rotaliform 
portion through the apertures of the early chambers. 
In connection with this, another very interesting fact was noted 
in regard to the coloration of the initial portion of the test. It 
