Freshwater Bryozoa, with descriptions of new Species. 191 
sketched out within the cell of the parent, its own chamber ra- 
pidly forms. and in the course of a day or two, the muscles in 
connexion with the orifice being added, the fresh-born member of 
the community bursts from the extremity of its cell, and is ready 
to take upon itself the work of its own maintenance. 
The development of the bud in Plumatella differs in no respect 
from that of Fredericella ; and in Paludicella there is no very im- 
portant deviation, except at the commencement of the process. 
In this the first apparent step in the growth of a new polype is 
the preparation of a distinct cell for its reception. If the top of 
the last-formed cell be carefully examined, even before its tenant 
is fully grown, the linmg membrane may be seen terminating in 
a blind sac, Pl. IV. fig. 4.0', a little below the extremity. Within 
this extremity will also be observed a membranous sac, /; at first 
the base of this sac is moulded on the convex blind termination 
of the lining of the old cell. The convexity however soon flat- 
tens and the sac rapidly increases in size, the external horny 
covering becoming at the same time elongated and attenuated. 
After awhile, an oval, somewhat opake body, the new bud, fig. 5 m, 
germinates from the mner surface of the lming membrane, J. 
This body is attached by its side to the front wall of the cell, and 
resembles the young bud in Fredericella. A long and very deli- 
cate membranous sac, fig. 6 d, afterwards the tentacular sheath, is 
now observed to be forming im contact with and above the oval 
bud; whilst from the lower extremity filaments, e, are seen to be 
produced which form the polype-retractors. From the upper end of 
the bud, the tentacles, fig. 4 d, soon make their appearance within 
the lower part of the membranous sheath, 7; at first very short, 
no more than the scalloped margin of the cup-formed disc ; but 
rapidly lengthening, fig. 5 a, they soon advance more than halfway 
up the sheath. The polype-retractors, figs. 47 & 5 g, by this time 
are considerably developed, and the retractors, k, 2, of the tube 
are distinctly visible ; the tube, fig. 47, now begins to bulge, and 
the inverted margins of the orifice are seen within, united to the 
upper end of the tentacular sheath: the parietal muscles, h, also 
make their appearance at this time, and the stomach, c, intestine, 
d, esophagus, b, and tentacles having all assumed their proper 
forms, the young animal is ready for protrusion. The buds of 
Paludicella, however, do not all originate from the extremity of 
the old cell ; sone sprout from the side, and then a slight swell- 
ing takes place on the inner surface of the tunic. The horny 
sheath soon afterwards begins to bulge, and an external cell 
being formed with its liming membrane, an oval bud makes its 
appearance, and development goes on as just described. 
It has been long known that these animals propagate by eggs 
as well as buds; Raspail appears to have described the anatomy 
