HEEMAPHRODITISM IN MOLLUSOA. 45 



EXPLANATION OF PLATES 4, 5, & 6, 



Illustrating Dr. Pelseneer's paper on " Hermaphroditism in 



Mollusca." 



Fig. 1. — Hermaphrodite reproductive apparatus ofOncIiidiopsis green- 

 landica, dorsal view, i, ovotestis ; ii, oviduct; iii, mucous gland; iv, 

 receptaculum seminis ; v, penis ; vi, sperniiduct ; vii, female aperture ; viii, 

 prostate ; ix, sperm-oviduct ; x, vesicula seminalis. 



Tig. 2. — Transverse section of the ovotestis ofOnchidiopsis. 



Fig. 3. — Part of the ovotestis of Onchidiopsis, slightly magnified, show- 

 ing male (white) and female (grey) portions. 



Fig. 4. — Ostrea cochlear, male, left view, i, rectum; ii, testis; lii, 

 internal plate of left gill ; iv, internal plate of right gill ; v, pallial suture ; 

 VI, adductor muscle ; vii, auricle ; viii, ventricle. 



Fig. 5. — Ostrea cochlear, female, left view, i, liver, seen by trans- 

 parency through the ovary ; ii, auricle ; iii, pallial suture ; iv, abductor 

 muscle ; v, intestine ; vi, ventricle. 



Fig. 6. — Ostrea cochlear, ventral aspect, mantle and gills removed. 



I, right genital aperture; ii, right renal aperture; iii, visceral ganglia; 



IV, outline of the mantle ; v, adductor muscle ; vi, visceral commissure ; vii, 

 branchial nerve ; viii, left renal aperture ; ix, left genital aperture ; x, palps 

 (the lines of adhesion of the gills to the visceral mass are indicated by dotted 

 lines). 



Fig. 7. — Transverse section of a female Ostrea cochlear, i, intestine; 



II, right lobe of the mantle; iii, nephridium ; iv, branchial axis; v, genital 

 aperture ; vi, visceral commissure ; vii, external plate of the right gill ; viii, 

 internal (adaxial) plate of right gill; ix, visceral commissure (left half); 

 X, renal aperture; xi, reno-pericardial duct; xii, ovary; xili, pericardium; 

 XIV, ventricle ; XV, left lobe of the mantle ; xvi, rectum ; xvii, auricles joined 

 together. 



Fig. 8. — Transverse section of a male Ostrea cochlear, i, right lobe of 

 the mantle; ii, branchial axis; ill, testis; iv, external plate of right gill; 



V, visceral commissure ; vi, internal plate of right gill ; vii, visceral com- 

 missure ; VIII, genital aperture ; ix, nephridium ; x, testis ; xi, pericardium ; 

 XII, ventricle (on the pericardial wall of which are modified epithelial cells 

 = pericardial glands) ; xiii, left lobe of the mantle ; xiv, rectum ; xv, 

 auricle ; xvi, intestine. 



Fig. 9. — Transverse section of the ovotestis of Cardium oblongum. 



