NUDIBRANCHIATE GASTEROPODA. 



EXPLANATION OF THE PLATES. 



Most of the figures are drawn by means of the camera lucida. 



PI. I. 



Bathydoris Imjolfiana, Bgh. 



Fig. i. The animal, from behind. Natural size. 



— 2. The same, from before. Natural size. 



— 3. One of the papulae of the back. 



— 4. The bulbus pharyngeus, lateral view. Natural size, a the labial disk, /' the region of the 



outer margin of the mandible, c the radula-sheath, d the oesophagus, c the duet of the sali- 

 vary gland with its ampulla. 

 5. The tongue with a the radula, behind this the tectum radulae, and hindmost b the end of 

 the radula-sheath. 



— 6. The mandibles, from before, a the upper end. Natural size. 



— 7. A piece of the median part of the radula, with a median tooth, and bb innermost lateral tooth. 



x 100 diam. 

 8. Median tooth, x 200 diam. 



— 9. First lateral tooth, x 100 diam. 



— 10. The same, lateral view, x 100 diam. 



— n. Two of the largest lateral teeth, x 100 diam. 



12. Outermost part of a series of teeth with 11 tooth-plates, a the outermost one. x 100 diam. 



- 13. One of the outer tooth-plates, lateral view, x 100 diam. 



— 14. A couple of the outermost tooth-plates, from above, x 100 diam. 



— 15. (abnormal) double tooth-plate, x 100 diam. 



- 16. The hermaphrodite gland, from its upper side. 



— 17. Follicles of the hermaphrodite gland. 



18. The anterior genital mass; a the mucous gland, b the spermatheca, in front of and upon it 

 the penis bag, c the coalesced genital vulvarian folds. 



19. a the duct of the hermaphrodite gland, b oviduct, c seminal duct, d the base of the praepu- 

 tium, c glans penis, f the aperture on its point. 



— 20. a seminal duct, b glans penis, slit longitudinally, with the continuation of the seminal duct 



to the aperture c on its point. 



