76 



Dr. U. P. Cowles on the Bodj -cavities and 



Fijr. 5. 



Fig. 4. — Longitudinal section through larva with two tentacles, X 704. 

 c.c, collar-cavity ; c.t.r., ciliated tentacular ring ; g.., ganglion ; 

 m}, mesentery between lobe- and collar-cavities : .r., indication 

 of a mesodermal sac. 



Fig. 5. — Longitudinal section through an Actinotrocha from Beaufort 

 Harbour, x 112. a. c.c, adult collar-cavity ; b.c, blnod-cor- 

 puscles; c.c, larval collar-cavity; d.m., indication of dorsal 

 mesentery; d.r., dorsal blond-vessel ; g., ganglion; 7w.', mesen- 

 tery between lobe- and collar-cavities ; wj.", mesentery between 

 collar- and trunk-cavities ; p.o.c, preoral body-cavity ; p.r. peri- 

 anal ring ; p.s., perianal sinus ; sen.p., sensory papilla ; t.r., trunk- 

 cavity ; v.7n., ventral mesenterj' ; r.j)., ventral pouch. 



