46' PAUL PELSENEKR. 



Fig. 10. — Transverse section of the abdomen of Pecten flexuosus, 

 showing male and female halves of the ovotestis. I, intestine. 



Fig. 11. — Longitudinal section of the right genital gland of Cyclas 

 cornea (the anterior part is below), i, epithelium of the visceral mass; ii, 

 testis ; iii, part of the genital duct between testis and ovary ; iv, ovary. 



Fig. 12. — Cyclas cornea, left view, without left gill and pallial lobe. 

 I, anterior retractor of the foot ; ll, anterior adductor ; iii, palp ; iv, foot ; 

 V, ovary ; VI, genital aperture ; vii, visceral ganglion ; vill, posterior ad- 

 ductor ; IX, posterior retractor of the foot ; x, kidney ; xi, rectum ; xii, 

 auriculo-ventricular slit ; xiii, ventricle ; xiv, testis ; xv, liver mass. 



Fig. 13. — Plan of nervous system, and genital and renal apertures in an 

 ordinary Lamellibranch i, cerebral ganglion ; ii, visceral commissure ; iii, 

 pedal ganglia; iv, genital aperture; v, renal aperture; vi, visceral ganglia. 



Fig. 14. — Plan of nervous system, and genital and renal apertures in 

 Anatinacea. i — iii, and v, vi, as in Fig. 13 ; iv, female aperture ; vii, male 

 aperture. 



Fig. 15. — Transverse section of Clavagella passing through the male 

 apertures. l, ovary; li, aorta; ill, mantle; iv, branchial axis; v, visceral 

 commissure ; vi, spermiduct ; vii, foot ; viii, testis ; ix, pad of adhesion of 

 the reflected internal lamella of the gill ; x, right male aperture ; xi, branchial 

 axis; xii, ovary; xiil, auricle; xiv, intestine; xv, pericardium. 



Fig. 16. — Transverse section of Clavagella (posterior to Fig. 15), passing 

 through the female apertures, i, ovary ; ii, aorta ; iii, intestine ; iv, ovary ; 

 V, visceral commissure ; vi, foot ; vii, pad of ciliated adhesion of the internal 

 reflected lamella of the gill ; viii, female aperture ; ix, branchial axis ; x, 

 nephridium ; xi, auricle ; xii, mantle ; xiii, pericardium. 



