518 



ALFRED 0. HADDON. 



ment of this process. It will be noticed that the inferior por- 

 tion of the area which is being constricted off is connected with 

 funicuhir tissue ; as a matter of fact, there is often a slight 

 difference in the character of those cells which occupy a corre- 

 sponding position in yet earlier buds. While this has been 

 happening, the other portion, which has a plate-like form, 

 becomes crenulated along its margin, the crenulations, which 

 point upwards and rather inwards, increase in size and we 

 have some twenty-two incipient oval tentacles formed. These 

 tentacles are thus early ranged into a circular lophophore, 

 continuous except in that region from which the above- 

 mentioned pouch is hanging. This gives an appearance of 

 bilateral symmetry to the lophophore, as was noticed by Allman 

 in Paludicella (19), and Nitschein Flustra membranacea 

 (13) (PI. XXXVII, figs. 4 and 5.). 



The developing polypide now consists of a disc-like body 

 (lophophore), surrounded by twenty-two oval tentacles, emar- 

 ginated at one spot from which depends a caecal pear-shaped 

 bag — the future stomach and intestine. 



A circular depression occurs towards one end of the disc of 

 the lophophore which rapidly deepens into a rounded sack 

 (PI. XXXVIIj figs. 6 and 7). The fundus of this sac impinges 



Pig. 1. — Diagram showing the relations of the developing bud in a Marine 

 Polyzoan. a, anus; b. b., brown body; c. p., coininunication phite ; 

 ed., ectocyst ; cp., cpiblast ; /., funiculus ; int., intestine ; ?«., mesobhist ; 

 (£., oesophagus ; r. m., retractor muscle ; st., stomach ; (., tentacles ; 

 i. s., tentacular sheath, 



