PLATE XI. 
Fig. 1. Fiona marina (Forsk&l). 
Fig. 1. Loose plates of the radula, lying beneath the tongue in a, hindermost part of the buccal cavity 
(beneath the tongue). Cam. luc. x 100 diam. 
Fig. 2. Cuthonella abyssicola, Bergh. 
Fig. 2. Part of masticatory edge ; a, hindermost part. Cam. luc. x 350 diam. 
Figs. 3-15. Marionia occidentalis, Bergh. 
Fig. 3. The central nervous system, from the under side ; a, b, cerebro-pleural ganglia, with the 
otocysts ; c, c, pedal ganglia; d, the united commissures; e, nervus genitalis; /,/, cerebro- 
buccal connective ; g, buccal ganglia ; h, h, gastro-cesophageal ganglia ; i, the eye. Cam. 
luc. x 55 diam. 
Fig. ' 4. The mandibles, from the anterior side ; a, masticatory processes. Cam. luc. 
Fig. 5. Part of the masticatory edge, from the inside ; a, posterior part ; b, anterior part. Cam. luc- 
x 350 diam. 
Fig. 6. Upper part of the masticatory edge in the neighbourhood of the hinge, from the outside ; a, 
anterior margin. Cam. luc. x 350 diam. 
Fig. 7. Pihachidian part of the radula with two series ; a, a, median plates ; b, b, first lateral plates. 
Cam. luc. x 350 diam. 
Fig. 8. Lateral plates, obliquely from the side. Cam. luc. x 350 diam. 
Fig. 9. Lateral plate, from the side. Cam. luc. x 350 diam. 
Fig. 10. Lateral plates, obliquely from the side. Cam. luc. x 350 diam. 
Fig. 11. Outer part of a series of plates with four plates ; a, outermost. Cam. luc. x 350 diam. 
Fig. 12. The hook of a lateral plate. Cam. luc. x 750 diam. 
Fig. 13. The largest of the stomachal plates. Cam. luc. x 55 diam. 
Fig. 14 a, Spermatheca ; b, its duct ; c, vagina ; d, vas deferens ; e, glans penis. 
Fig. 15. End of the glans penis ; a, orifice of the seminal duct. Cam. luc. x 100 diam. 
Figs. 16-19. Tritonia challengeriana, Bergh. 
Fig. 16. The mandibles from the anterior side ; a , masticatory processes. Cam. luc. 
Fig. 17. Part of the masticatory edge ; a, innermost part; b, anterior margin. Cam. luc. x 350 diam. 
Fig. 18. Ilhacbidian part of a series of plates ; a, median ; b, b, first lateral plates ; c, third plate. 
Cam. luc. x 350 diam. 
Fig. 19. aa, Ductus ejaculatorius ; b, prseputium ; c, c, musculi retractores penis ; d, glans penis. 
Fig. 20. Scyllcea pelagica, Linn A 
Fig. 20. a, End of the ductus ejaculatorius ; b, the half of the prseputium taken away and the glans 
penis denuded. 
