G1 
these appear subsequently to coalesce, and ultimately form a 
single large oval or somewhat reniform body, which clothes 
itself in a firm, dark brown, ehitinous capsule, and, after the 
disappearance of the polypide, remains behind in the tube 
(fig. 1, e, e, and fig. 3). I regard it as a statoblast. The 
formation of statoblasts in Rhabdopleura would thus cor- 
respond in most points to what we know of their formation 
in Plumatellce, Alcyonella, and other freshwater phylacto- 
ccematous polyzoa where they are also developed in the sub- 
stance of the funiculus. The statoblasts of Rhabdopleura, 
however, differ from the corresponding bodies in the fresh- 
water genera by being less definite in form and size. Their 
contents consist of clear spherical bodies resembling cells, 
but destitute of distinct nucleus. My specimens afford no 
evidence of any portion of the animal specially devoted to 
the formation of ova or of spermatozoa. 
By the aid of acetic acid it was possible, in some of the 
younger parts of the camfecium, to separate the endocyst 
from the investing ectocyst as a very delicate membrane ; 
only faint indications were obtained of that portion of it 
which, during the retracted state of the polypide, becomes 
reflected over the tentacles, so as to form the tentacular 
sheath. 
In some parts of the ccencccium the polypides may be seen 
in various stages of maturity, and an opportunity has been 
thus afforded to me of determining some important points 
in the development of the bud. 
In a very early state (fig.5) the bud may be seen as a minute, 
flattened, somewhat rhomboidal body, attached by a short thick 
peduncle, the rudimental funiculus, to a little proGess of the 
rod similar to that which gives attachment to the funiculus 
of the adult polypide. In a slightly more advanced stage 
(fig. 6) the bud has somewhat increased in size, and there 
may be now seen, projecting from its distal edge, two short, 
cylindrical, tentacula-like processes (6). Careful exami- 
nation now renders it evident that the greater part of the 
bud is enclosed between two fleshy plates (a) united to one 
another in a part of their circumference, and free in the 
remainder. It is from between the two plates, where their 
edges remain disunited, that the two tentacular processes 
project. These processes are the two arms of the crescentric 
lophophore, showing, as yet, however, no trace of tentacles. 
In a more advanced stage (fig. 7) all theparts have still further 
increased in size, the arms of the lophophore ( b ) project to a 
greater distance from between the edges of the right and left 
valve-like plates, and each carries a double series of minute 
hemispherical tubercles ; these are the rudiments of the ten- 
