Freshwater Bryozoa, with descriptions of new Species. 208 
tella Allmani: a, mouth; 6, oral valve; cc, oral arms ; d, mem- 
brane at base of tentacles. 
Fig. 4. Much-enlarged view of the reproductive organs of Fredericella sul- 
tana: aa, outer wall of cell; 5 6, linimg membrane or tunic; 
c, lower portion of stomach ; d d, ovary ; e, egg imbedded in same ; 
J, two filaments attached to the lower end of stomach, probably 
connected with the reproductive system ; g, retractor muscles. 
Fig. 5. Enlarged view of a cell of Plumatella Alimani exhibiting reproduc- 
tive organs: a, pase of oral arms; 5, cesophagus; c, stomach ; 
d, intestine ; ; ee, ovary; f, egg nearly mature, still attached to 
ditto ; g, an egg just forming likewise attached to ovary ; hh, two 
Giniients attached to the aotiaeht probably connected with the 
reproductive system; 77, the two bundles of retractor muscles ; 
j, outer wall of cell; &, lhmmg membrane or tunic. 
Puate IV. 
Fig. 1. Enlarged view of a cell of Paludicella procumbens seen as a trans- 
parent object, the polype being exserted: aa, outer wall of cell; 
666, limmg membrane or tunic ; c, tubular orifice ; d, membranous 
cup surmounting ditto; e, tentacular disc ; f, tentacles; g, pha- 
ryngeal swelling ; 4, cesophagus; 7, stomach; 7, mtestine ; k, en- 
largement at commencement of ditto; 7, anus ; m, supposed ovary ; 
n, filament attached to the lower extremity of stomach, probably 
connected with the reproductive system; 0, polype retractor 
muscles; pp, inferior tube-retractors; g, two fibres of superior 
tube-retractors ; 77, muscles to prevent the complete version of 
tentacular sheath ; s, tentacular sheath doubled upon itself ; ¢, pa- 
rietal muscles; wu, end-walls of two cells abutting against each 
other. 
Fig. 2. Enlarged view of a single cell of P. procumbens with polype re- 
tracted: a, outer wall of cell; 5, ling membrane of ditto ; ¢, re- 
tracted tubular orifice; d, tentacles; d! d', tentacular sheath ; e, 
cesophagus ; f, cardiac orifice ; g, stomach ; h, intestine ; 7, enlarged 
portion of ditto ; 7, supposed ovary doubled upon itself; &, filament 
attached to lower end of stomach, probably connected with repro- 
ductive system ; //, polype retractor muscles ; mm, inferior tube- 
retractors ; nn, superior tube-retractors ; 0, sphincter muscles for 
closing orifice ; p, do. do.; g g, muscles to prevent complete in- 
version of tentacular sheath ; r, end-wall of cell formed by the 
tunic exhibiting enlargement in the centre. 
Fig. 3. End of retracted tube of P. procumbens exhibitmg the manner in 
which it folds in. 
Fig. 4. Termimation of a branch of P. procumbens comprising two cells in 
different stages of development: a, outer wall of cell in fourth 
stage of development ; 0, lmmg membrane of ditto; 5', blind ter- 
arnt of do. do.; ce, place of future orifice ; “y fentanies of 
polype in state of development ; e, cesophagus ; f, stomach ; g, in- 
teste ; h, lower reproductive organ; 7, tentacular sheath ; j, po- 
lype retractor muscles ; k, tube-retractors ; /, new cell in first or 
earliest stage of development, exhibiting liming membrane and ex- 
ternal wall; m, nucleated cells in linimg membrane. 
Fig. 5. Two terminal cells of P. procumbens containing buds in different 
stages of development: a, tentacles of bud far advanced or in 
fifth stage of development ; a’, tentacular sheath; 6, oesophagus ; 
e, stomach ; d, intestine ; e, anus; f, lower reproductive organ ; 
i. polype-retractors ; h, parietal muscles ; 7, tube-retractors ; 7, ube 
