392 Prof. J. Reid on the Anatomy and 
body are developed. In the beginning of October I procured 
several specimens in which a large mass of cells (ova) was placed 
im the space between the gullet, intestine and upper edge of the 
stomach (fig. 84), extending downwards to the entrance of the 
gullet into the stomach, and depressing the stomach and forcing 
it considerably downwards. In two of these this mass of cells 
projected into the interior of the gullet near its lower part, and 
exceedingly minute ciliated ova were seen escaping from the 
upper part of the cellular mass, and several were also seen swim- 
ming in the interior of the eullet and stomach. Portions of this 
mass of cells were after a time extruded outwards, and were com- 
posed of the ciliated ova, and of very minute nucleated cells con- 
nected together by a structureless substance. Many of these ova 
formed a single cell, broader at one end than at the other, witha 
circle of cilia longer than the cell placed around the margin of 
the broad end (fig. 9 a), while others presented one, two or more 
very minute cells attached to its lower or narrow extremity 
(fig. 94 &c). The nucleated cells consisted of a cell-membrane 
with two or more nuclei, and appeared to be undeveloped ova. 
The ciliated ova swam actively about, sometimes bending all 
their cilia in the same direction, forming a curved bundle and 
striking in the same line for some time together, at other times 
spreading their cilia and moving them in different directions. 
These ova are so minute as to require very high magnifying powers 
for their examination. It would thus appear “that this polype, sup- 
posing all the individual animals whose stalks are attached to the 
same creeping stem to form one aggregate animal, extends and 
prolongs the life of the individuals composing it in two ways ; viz. 
by renewal of the individual bodies after they have dropt off, and 
by offsets of new individuals from the creeping stem; and that it 
reproduces and extends the species, or forms new aggregate ani- 
mals, by the formation of ciliated cells. I have never been able 
to detect any circulation of nutritious juices in the stalk, though 
examined under the most favourable circumstances. 
Crisia chelata. This polype when extruded affords a good 
view of the membrane connecting the outer surface of the pha- 
rynx and rectum together (fig. 10a). It would be more correct 
to say, connecting the supporting part of the tentacula and rec- 
tum together, for the pharynx, as in the other ascidian polypes, 
lies loose, and can be seen contractmg, within this supporting 
part. It protrudes itself through a small opening at the upper 
margin of the cell, and the large opening seen in the dead spe- 
cimen on the anterior surface of the cell, is m the living speci- 
men covered in by a membrane. The polype has from ten to 
twelve ciliated tentacula about half the length of the cell. The 
dilatation of the digestive tube (stomach) at the termination of 
