PLATE II. 

 FIGS. 8-9c. Adacnarca nitrns. 



FIG. 8. Transverse section, showing c.e., cephalic eye ; i.d., inner demibranch ; ov. ovum. 

 FIG. SA. Left gill. 



fl.f.i., Direct filaments of inner demibranch ; i.d., inner demibranch ; r.f.l., reflected 



filaments of inner demibranch ; r.f.n., ends of reflected filaments of outer demibranch. 

 FIG. OA. Transverse section through renal orifice, showing extension of mantle-cavity between the 



attachments of the outer and inner demibranchs. 

 FIG. 9e. Transverse section through region of transference of attachment of outer demibranch from 



mantle to body, showing extension of mantle-cavity in body-wall above gill-attachment. 

 FIG. 9c. Transverse section through visceral ganglion, showing hinder termination of extension of 



inaiitle-cavity. 

 FIGS. OA-C. c.v.c., Gerebro-visceral connective ; cp.r., sub-branchial epithelial ridge ; !.d., inner demibranch ; 



m.c., extension of mantle-cavity; u.d., outer demibranch; r., renal organ; v.g., visceral 



ganglion. 



FIGS. 10-12. Liiitopsis grand! f. 



FIG. 10. Diagram of the internal anatomy. 



iibd.o., Adominal sense-organ ; a.r.p., anterior retractor pedis ; an., auricle ; au.c., 

 auricular communication ; /;/.., gill-axis of left side ; lir.in., branchial muscle ; by.p., byssal 

 papilla ; ext., curtain-like extension of outer lip ; (j.iL, genital duct ; ij.i. gastro-intestine ; 

 o., otocyst ; <>.!., outer lip ; p.r.p., posterior retractor pedis ; ., renal organ ; r.pc.d., reno- 

 pericardial duct ; u.i/.u., urinogenital orifice ; ., ventricle. 

 FIG. 11. Lips in transverse section. 



ext., Extension of outer lip ; /./., inner lip ; w., mantle ; o.l. outer lip. 

 FIG. 12. Gill-axis in transverse section. 



In-. n., Branchial nerve; <., cartilaginoid tissue; wi., branchial muscle. 



