PLATE IV. 



FIGS. 20-23, 25. Anatina elliptica. 

 FIG. 24. Anatina truncata. 



FIG. 20. Diagram of the general anatomy of Anatina elliptica. 



A B plane of section of Figs. 21, 23. a.i.d., Line of attachment of inner demibranch ; 

 a.o.cL, line of attachment of outer demibranch ; ti.r.p., anterior retractor pedis ; I.e., byssal 

 cleft ; br.ii., branchial nerve ; </.., expanded gill-axis ; i.d., inner demibranch ; Jc.o., Keber's 

 organ ; o., passage between outer demibranch and mantle ; o.tl., outer demibranch ; 

 p.c., pericardium ; p.o., pedal orifice ; p.r.p., posterior retractor pedis ; r., kidney ; r.c., renal 

 communication ; r.p., proximal arm of kidney ; r.pc.d., reno-pericardial duct ; s.s., siphonal 

 septum ; u.r/.c., mouth of urinogenital canal. 



FIG. 21. Diagram of urinogenital canal and genital and urinary ducts, from ventral (posterior) aspect 

 (plane of section shown in Fig. 20, A B ; lettering as in Fig. 23). 



FIG. 22. Diagram of urinogenital canal and genital and urinary duets, postero-dorsal aspect (lettering as 

 in Fig. 23). 



FIGS. 23A, B, c. Sections in plane A is, Fig. 20, through the mouth of the male duct (A), through the 

 renal orifice and oviduct (B), and through the urinogenital canal (c). 



Lr.n., Branchial nerve ; c.v.c., cerebro-visceral connective ; m.d., male duct ; o., ovum ; 

 o.il., oviduct ; r., distal arm of kidney ; )./., attachment of reflected lamina ; r.o., renal 

 orifice ; ii.y.c., urinogenital canal. 



FIG. 24. Diagram of genital and urinary ducts of Anatina truncata from above (compare Fig. 22). 



c.v.c. , Cerebro-visceral connective; ni.rL, male duct; o.d., oviduct; ov., ovary; p.c., 

 posterior horn of pericardium ; ;., distal arm of kidney ; r.d., renal duct : r.pc.d., reno-peri- 

 cardial duct ; u.fj.c., urinogeuital canal. 



FIG. 25. Diagram of gill and gill-axis, in transverse section, of Anatina elliptica. 



f/.a., Expanded gill-axis ; i.d., inner demibranch ; o.d., outer demibrauch ; sp.c., supra- 

 branchial chamber. 



