350 SIDNEY F. HARMER. 



Fig. 65. — Basal view of a B-zoceciiim (basal wall removed). The cryplo- 

 cjst {ciypl.) is seen from ifs basal surface; part, of the floor of the 

 lateral recesses (/. r.) is broken away. Between the two recesses is the 

 passage {tube) by which the tentacle sheath passes to the orifice ; 

 occl.', distal occlusors, with their transverse fascia ( /.') ; occl., proximal 

 occlusor, with its tendon {tend.); depr., depressor muscles of frontal 

 membrane; div., divaricalor muscles of operculum; m.s., main sclorite of 

 operculum. The movements of the tentacle siieath are restrained by 

 four delicate muscles, two of which originate from the wall of the tube. 



Fig. 66. — Frontal view of a B-zocecium ; occl.t., occlusor tubercle; 

 lig., hiuge-ligaments, connecting the condyles {cond.') with the ends of 

 the basal sclerite {b. *.) ; f. m., frontal membrane, into which the 

 depressor muscles (depr.) are inserted; vi.pr., median process, arising 

 from the roof of the tube (of. Fig. 65) ; other letters as in Fig. 65. 



Postscript. — Since this paper was sent to press I have 

 received from Dr. G. M. R. Levinseu a copy of his recently 

 published preliminary note entitled " Studies on Bryozoa ^' 

 (' Vidensk. Medd. fra den Naturh. Foren. i Kjobenhavn,' 

 1902). The paper deals with the morphology to the Chei- 

 lostomata, and the questions considered are largely identical 

 with those to which 1 have here paid attention. Dr. Levinsen's 

 contribution is too important to be discussed within the limits 

 of a postscript. — S. F. H. 



Julv 27th, 1902. 



