70 



CEYLON PEAEL OYSTER RErOKT. 



EXPLANATION OF PLATES. 

 List of Beference Letters. 



Add., adductor muscle. 



Add.', peripheral portion of Add. 



Add.", central portion. 



Add.'", adductor impression. 



An. or a., anus. 



An.f., anal funnel. 



Ao.a., anterior aorta. 



Ao.p., posterior aorta. 



Art.a.p., anterior pallial artery. 



Art.c.p., common pallial artery. 



Art.h.p., hepato-pedal artery. 



Ji1.ji.jk, right posterior pallial artery. 



Art.p.p.', left, ,, 



Art.vis., visceral artery. 



Aa., auricles. 



B.r., blood corpuscles. 



Br., branchiae. 



Br.aff., common afferent branchial vessel. 



Br.eff., efferent ,, 



Br.int., internal branchia. 



By., byssus. 



By.d.p., byssus disc-pit. 



By.p., byssal pouch. 



By.p.', pleated surface of byssal gland. 



By.p.gl., glands forming byssus. 



By.r., root of byssus. 



By.s., byssal sinus. 



By.t., byssal tube, or groove. 



C.c, granular cells with concretions. 



C.d., ciliated disc. 



Cer.g., cerebral ganglion. 



C.p.con., cerebro-pedal connective. 



Ct., ctenidium. 



CI. a., ctenidial axis. 



C.v.con., cerebro-visceral connective. 



D.a.L, antero-lateral hepatic duct. 



D.gl., digestive gland. 



U.p.i., pre-intestinal duct. 



ll.ji.J., jiostero-lateral duct. 



D.p.v., postero-ventral duct. 



D.S.C., sub-central duct. 



D.sm'., sub-cesophageal duct. 



Em.o., excivrrent orifice. 



F., foot. 



F.Iii/.ji., folds of byssal gland. 



Fib.ret., fibres of retractor muscle. 



G.f., gill filament. 



Go., gonad. 



Go.', external aperture of gonad. 



I.l.j., inter-lamellar junction. 



Int.ap., intestinal aperture in stomach. 



Int.lp., intestinal loop. 



Int. 1, descending intestine. 



Int. 2, ascending 



Int. 3, rectum. 



Lev.a., anterior levator muscles. 



Lev.p., posterior 



IAg., ligament. 



M.b., muscle bundle. 



Mg.pall., pallial margin. 



Mg.vel., edge of velum. 



My., muscular tissue. 



N., or n., nerve. 



JY.br., branchial nerve. 



Ncph., sac of nephridium. 



Neph.', glandular portion of nephridium. 



N.pal., pallial nerves. 



Np.con., channel between nephridia. 



N.s.o., nerve to pallial sense organ. 



0., mouth. 



Oe., oesophagus. 



Org., organic connection in branchiae. 



Os., osphradium. 



Pa., labial palps. 



Pa.d., dorsal palp. 



Pall.', centre of pallial lobe. 



Pall.", muscular region of mantle. 



Pall.ril.h., pallial ciliary band. 



Pall.f., pallial fold (opposite tips of branchiae). 



Par.sp.g., parieto-splanchnic ganglia. 



Pa.v., ventral palp. 



Ped.g., pedal ganglion. 



Ped.loc, locomotor part of foot. 



Per., pericardium. 



Per.ar., supra-rectal pericardial arch. 



Per.ostr., periostracum of shell. 



P.f., principal filament in gills. 



P.i.dep., pre-intestinal depression. 



Pl.fl., dendritic plate of stomach. 



Pr.dig., digitate process of valve. 



