PLATE I. 

 FIGS. 1-7. Lissfii-ca notorcadensis. 



FIG. 1. Diagram of Lissarca notorcadensis. 



ii., Anus ; ab.o., abdominal sense organ ; add., adductor ; a.r.jt., anterior retractor pedis ; 

 li/., byssus; bi/.p., byssal papilla; c.e., cephalic eye; e.p., elevator pedis; g.a., gill-axis; 

 g.int., gastro-intestine ; g.o., genital orifice ; /(., heart; i.il., inner demibranch ; i.Z., inner lip ; 

 Int., intestine ; I.e., labial csecum ; pc., pericardium ; ji.;/., pedal ganglia; p.r.p., posterior 

 retractor pedis; ., otocyst ; o.J., outer lip; ., renal organ; r.o., renal orifice; ;-.^<v/., reno- 

 pericardial duct. 

 FIG. 2. Mantle-edge in transverse section. 



/./., Inner fold ; m.f., middle fold ; o./., outer fold. 



FIG. 3. Posterior end of inner palp and commencement of inner demibranch, showing position of 

 cephalic eye. 



C.C., Cephalic eye; /'., swollen anterior filament of inner demibranch; id., inner 

 demibranch ; ipl}*., inner palp. 

 FIG. 4. Transverse section through cephalic eye. 



e., Eye ; id., inner demibranch. 



Fins. 5A, SB. Transverse sections at different levels through the lips (Fig. 5A) and palps (Fig. SB), showing 

 the entry to and position of the labial ca-cum. 



c.i/., Cerebral ganglion ; It. p., hepato-pancreas : /./., inner lip ; i.plji., inner palp ; I.e., labial 

 c<ecum ; -in., mantle ; o./., outer lip ; o.plp., outer palp ; ov., ovary. 

 FIG. 6. Transverse section through labial caecum. 



/./., Inner lip ; I.e., labial caecum. 



F IG . 7. Transverse section through the anterior extremity of the sub-branchial epithelial ridge. 

 ep.r., Epithelial ridge; i.g., attachment of inner demibranch. 



