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of the adult Bryozoon, and when first observed was enclosed 
in a delicate, transparent, egg-shaped sac, through which the 
various parts of the contained embryo might be seen with 
ease. 
Within this external sac the embryo is suspended in a 
transparent cell, the rudiment of the future polypedom, and 
presents distinct traces of tentacula, stomach, and intestines. 
‘The rudimentary muscles may also be plainly seen. The 
tentacula are as yet very imperfect, they are short and thick, 
when compared with the same organs in the adult animal, 
and strongly suggest the idea of having been formed by the 
longitudinal division of what had been, in a still earlier stage, 
a continuous infundibuliform membrane. The cell or rudi- 
mental polypedom is of an oval figure, densely ciliated 
posteriorly. Where the cilia terminate, the membranous 
walls of the cell present an invagination to a considera- 
ble extent, and are again reflected outwards to undergo a still 
further invagination, by which a sheath is formed for the 
rudimental tentacula, and the digestive organs suspended in 
the visceral cavity. 
When the embryo Plumatella is released from the external 
egg-shaped envelope, its locomotive powers ‘being now no 
longer restrained, it soon becomes evident how active a crea- 
ture it is, for withdrawing the anterior portion of its cell, 
which, as we have already seen, is deprived of cilia, within 
the posterior ciliated portion, the latter is completely closed 
around the anterior end, and the little embryo thus becomes 
closely wrapped in a natatory mantle, through whose agency 
it is carried through the surrounding fluid in endless and 
elegant gyrations, 
Beyond this point in the development of Plumatella, Dr. 
Allman was unable to adduce any observations; the little 
larva, however, now described, presenting as it does all the 
essential elements of bryozoal structure, belongs undoubtedly 
