190 Mr. A. Hancock on the Anatomy of the 



similar in all the Bryozoa, only those at the inferior extremity 

 of the stomach in the marine species appear deficient in the 

 freshwater forms. They all have, however, one or more appen- 

 dages to this part, but these we shall afterwards see are most 

 probably connected with the reproductive system. The parietal 

 and sphincter muscles are common to both Paludicella and the 

 marine forms. On the whole, then, in the muscular system as 

 well as in the digestive apparatus, Paludicella shows a close re- 

 lationship to Bowerbankia and its congeners ; and is, in fact, 

 an intermediate link between them and the other freshwater 

 Bryozoa. Even the minute structure of the muscles themselves 

 would seem to confirm this. In all they are composed of trans- 

 parent, linear tibres separated from each other and apparently 

 homogeneous. When broken they become irregularly nodulous ; 

 but I have not succeeded in detecting transverse strise observed 

 by Professor Allman, probably from having used insufficient mag- 

 nifying powers. The small knot-like swelling so remarkable in 

 the centre of the fibre of the marine species is not to be found in 

 either Plumatella or Fredericella ; in Paludicella, however, I have 

 observed it in the parietal, but in no other muscles. 



Reproductive System. — In the freshwater as in the marine 

 Bryozoa there are two methods of reproduction, — one by buds, 

 the other by eggs. The buds always germinate from the same 

 part of the cell, hence the definite form of the polypidom. In 

 Fredericella the germ is found in connexion with the inner sur- 

 face of the tunic not far below the orifice of the cell on its lower 

 side. As the bud enlarges the wall bulges, showing externally 

 the appearance of a new shoot. At first the bud, PI. II. fig. 3 a, 

 is small and oval, and is attached for nearly its whole length ; it, 

 fig. 2 o f soon becomes irregular in form, with the upper portion 

 broad and somewhat bifid, the lower extremity prolonged : the 

 upper portion then gradually exhibits a circle of short rudi- 

 mentary tentacles, fig. 4 / ; and the lower end is seen to be di- 

 vided longitudinally into oesophagus and intestine, fig. 5 b, d, 

 continuous at their lower extremities, which still elongating form 

 the stomach, figs. 4 m & 5 c. To this is seen an appended fila- 

 ment binding it below to the wall of the cell. Imbedded in this 

 filament there is a large, distinct globule with nucleus and nu- 

 cleolus : this we shall afterwards learn is the incipient ovum, 

 figs. 4 o & 5 e, lying in the ovary. The polype-retractors, 

 figs. 2 q & 4 n, now make their appearance, passing from the 

 tentacular base to the side of the cell formed apparently out of 

 the lower portion of the original attachment of the bud; the up- 

 per portion of this attachment dilating becomes the tentacular 

 sheath, fig. 2j9, into which the tentacles are gradually insinuated 

 as they are developed. The polype being now, as it were, 



