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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. 

 AUman 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 



