THE " TRITON " TUNICATA. 117 



Fig. 7. — Part of the prebranchial zone enclosed by the coiled dorsal ends of the peripharyngeal 

 band, from a specimen preserved in chromic acid and absolute alcohol, and stained 

 in picro-carmine. Objective, Zeiss, fy, oil immersion. 



Fig. 8. — The anterior half of the nerve ganglion, showing the origin of the neural duct, from 

 specimen stained in osmic acid. Objective, Zeiss, ^, oil immersion. 



Fig. 9. — Anterior end of the duct from the neural gland, showing its ciliated expansion and 

 terminal aperture, from specimen preserved in osmic acid and absolute alcohol. 

 Objective, Zeiss, y 1 ^, oil immersion. 



Fig. 10. — Posterior end of endostyle, oesophageal aperture, and the neighbouring part of the 

 branchial sac, seen from the interior, from a specimen preserved in chromic acid 

 and absolute alcohol, and stained in picro-carmine. Objective, Hart. 4. 



Fig. 11. — Part of the heart, from specimen shown in fig. 10. Objective, Hart. 7. 



Fig. 12. — Part of the ganglion, showing the origin of one of the nerves, from a specimen pre- 

 served in picric acid and absolute alcohol, and stained in picro-carmine. Objective, 

 Zeiss, y^, oil immersion. 



Fig. 13. — A group of nerve cells from the ganglion shown in figure 12. Enlarged from Zeiss, 

 Objective yV^, oil immersion, ocular 4. 



Plate XX. 



Doliolum denticulatum, Quoy and Gaimard. 



Fig. 1. — Oesophagus, stomach, intestine, digestive glands, reproductive organs, &c, of an 

 individual preserved in alcohol, and stained in picro-carmine. Reduced from 

 Objective, Swift, 1 inch. 



Fig. 2. — Part of the duct (d) crossing from intestine to stomach in last figure. Objective, 

 Zeiss, yV^, oil immersion. 



Fig. 3. — Part of the digestive gland forming a network of tubules over the intestine, from 

 same specimen as fig. 1. Objective, Swift, £ inch. 



Fig. 4. — Part of the wall of the intestine, surface view. Objective, Hart. 5. 



Fig. 5. — Part of the organ (gl) seen ramifying over the stomach and first portion of the 

 intestine in fig. 1, from specimen stained in picro-carmine. Objective, Zeiss, y^, 

 oil immersion. 



Fig. 6. — The reproductive system dissected out. Reduced from Objective, Swift, 1 inch. 



Fig. 7. — The same in another specimen, showing a curious anterior termination. Reduced from 

 Objective, Swift, 1 inch. 



Fig. 8. — Anterior extremity of the testis of another individual, stained in picro-carmine. Objec- 

 tive, Swift, 1 inch. 



Fig. 9. — Anterior extremity of the testis in another specimen, preserved in solution of 

 osmic acid. Objective, Hart. 5. 



Fig. 10. — Anterior extremity of the testis in another specimen, stained in picro-carmine. Objec- 

 tive, Swift, 1 inch. 



Fig. 11. — Anterior extremity of the testis in another specimen. Objective, Hart. 5. 



Fig. 12. — Small part of the edge of the testis near the posterior end. Objective, Hart. 7. 



Fig. 13. — Opening of vas deferens close to ovary. Objective, Hart. 4. 



Fig. 14. — Aperture of vas deferens. Objective, Hart. 7. 



VOL. XXXII. PART I. U 



