250 INTRODUCTION. 
Fig. VI. Genitalia. 1. Testicle; 2. epididymis ; 2." vas deferens ; 
3. accessory gland of epididymis; 4. prostate; 5. penis; 6. retractor 
of do. ; 7. ovary; 8. oviduct; 9. genital bladder; 10. vagina; 11- 
cloaca. 
Figs. VII. — IX. Auditory apparatus of H. pulchella. 
Fig. VII. Inferior ganglia of the sub-oesophageal mass, highly 
magnified, with the auditory vesicles attached. 
Fig. VIII. Side view of one of the auditory vesicles. 
Fig. IX. Otocouites, very highly magnified. 
PLATE X. 
Figs. I. — III. H. exoleta. 
Fig. I. Digestive apparatus. I. Buccal body; 2. lingual pouch; 
3. retractor of buccal body; 4. stomach; 5. intestine; 6. salivary gland; 
7. ducts of do.; 8. hepatic ducts. 
Fig. II. Genitalia. Same references as Fig. VI. PI. IX.; 2.*" glan- 
dular commencement of vas deferens. 
Fig. III. Penis laid open. 1. Longitudinal folds ; 2. vas deferens ; 
3. valvular folds ; 4. retractor of penis ; 5. vagina; 6. orifice of do. 
Figs. IV. V. H. elevata. 
Fig. IV. Viscera dissected apart. 1. Buccal body; 2. oesophagus; 
3. stomach; 4. intestine; 5. rectum; 6. anus; 7. salivary gland; 
8. liver; 9. testicle; 10. epididymis; 11. accessory gland of do. ; 10.* 
vas deferens ; 12. prostate; 13. penis; 14. retractor of do. ; 15. ovary; 
16. oviduct; 17. genital bladder; 18. pulmonary chamber; 19. pul- 
monary vein; 20. heart; 21. renal organ ; 22. duct of do.; 23. pulmo- 
nary orifice ; 24. supra-, 25. sub-oesophageal, and 26. stomato-gastric 
ganglia. 
Fig. V. Penis laid open. 1. Longitudinal folds of interior ; 2. vas 
deferens; 3. retractor of penis. 
FLATE XI. 
Figs. I— IV. II. Sayi. 
Fig. I. Digestive apparatus. 1. Buccal body; 2. retractor of do- ; 
3. lingual pouch ; 4. oesophagus ; 5. stomach; 6. intestine; 7. salivary 
gland; 8. salivary ducts ; 9. hepatic ducts. 
