194 Mr. A. Hancock on the Anatomy of the 
sembling Cercarie. I have detected similar bodies in Bower- 
bankia with large rounded heads and long tails ; they were very 
numerous, and moved rapidly about im the interior of the cell in 
the manner of tadpoles, that is, with a lateral undulating motion, 
and are assuredly Spermatozoa. A testis may then be expected 
to exist in the freshwater Bryozoa coextensively developed with 
the ovary, and from analogy to be associated with it. It is not 
unlikely therefore that these additional filaments from the stomach 
may be really the male organ. 
Each polype does not appear to produce more than two or 
three eggs; in Plumatella frequently only one. In P. Allmani 
they, Pl. III. fig.5 f, are considerably depressed, of an oval form, 
sometimes very long with the sides almost parallel ; they are very 
large, being sometimes almost as wide as the diameter of the cell, 
within which they are placed lengthwise ; the margins are reticu- 
lated, yellow, pellucid, thin, and sharp, forming a well-defined rim 
about the central portion, which is opake and black ; the covering 
is smooth, tough, aud membranous. In Fredericella the egg is 
broader and more regularly oval, of a brownish colour with the 
margin narrow, plain and of a paler hue. The egg, Pl. IV. fig. 7 e, 
of Paludicella, if egg it be, differs considerably from the above. 
It is of an irregular oval shape, about half as wide as the cell, 
colourless and pellucid; the surface is marked with a few indi- 
stinct, irregular, nucleated cells ; one larger and much more con- 
spicuous than the rest, with a distinct round nucleus in the cen- 
tre, is always to be seen on one side. The circumference of the 
ege exhibits a double margin indicating an enveloping shield. 
The great size of the egg forbids the possibility of its escape 
without the destruction of the polype*. In Plumatella, the 
* The polype of the marine species must also perish on the escape of the 
gemmule. On examining some specimens of Bowerbankia in August, al- 
most every cell was found to contaim a large, round, opake, bright yellow 
corpuscle. These corpuscles were for the most part in the lower portion of 
the cells ; some however were halfway up, and others not far from the top : 
those lowest down were the smallest, and as they approached the top they 
increased in size until their diameter was nearly equal to that of the cell. 
As long as the corpuscle remained near the lower extremity of the cell, the 
polype was alive and active; but was invariably dead when it had advanced 
far upwards. At first the corpuscle does not appear to have any envelope, 
but as it increases in size a distinct margin makes its appearance, which 
afterwards becoming wider and perfectly transparent, the corpuscle can 
be seen rotating within by the aid of the long cilia that clothe its sur- 
face. While watching one in this state under the microscope, I observed it 
gradually elongate itself and pass with a slow gliding motion to the top of 
the cell; then forcing its way through the previously closed orifice, and 
passing into the surrounding fiuid, commenced to rotate with extraordinary 
velocity : in an instant after this its envelopiig membrane was torn open 
and cast aside, and the little being, a broadly. ovate gemmule, dashed at 
once beyond the field of view. It afterwards kept moving about im various 
