Fig. 



1. 



Fig. 



2. 



rig. 



3. 



Fig. 



4. 



Fig. 



5. 



Fig. 



6. 



Fig. 



7. 



116 DR W. A. HERDMAN ON 



Fig. 4. — Dorsal part of anterior end of branchial sac of Ascidia virginea var. ■pcdnncidata, 

 showing tentacles, dorsal tubercle, &c. Objective Swift, 1 inch. 



Fig. 5. — Polycarpa pomaria, Savigny, seen from the left side. Natural size. 



Fig. 6. — Part of the branchial sac of Polycarpa pomaria, seen from the inside, and showing 

 two folds and two interspaces. Objective, Swift, 1 inch. 



Plate XVIIT. 



Doliolum denticulatum, Quoy and Gaimard. 



-Doliolum denticulatum from the right side. Natural size. 



-A specimen preserved in chromic acid and absolute alcohol, from the left side. 



Natural size. 

 -The same specimen seen from the ventral surface. 



-A young individual (2 mm. in length) seen from the right side. Objective, Hart. 4. 

 -Part of a muscle band from the mantle of a specimen preserved in picric acid. 



Objective, Hart. 5. 

 -Another muscle band from the same specimen. Objective, Hart. 5. 

 -Anterior half of endostyle, seen from the interior of the branchial sac, from specimen 

 stained in picro-carmine. Objective, Hart. 4. 

 Fig. 8. — Nerve ganglion, dorsal part of peripharyngeal band, &c, seen from interior of branchial 



sac. Objective, Hart. 4. 

 Fig. 9. — Broad barrel-like form of Doliolum denticulatum, from left side. Natural size. 

 Fig. 10. — Two specimens of the narrow elongated form. Natural size. 

 Fig. 11. — Right side of branchial sac, &c, from interior. Reduced from Objective, Hart. 4. 

 Fig. 12. — Nerve ganglion, neural duct, peripharyngeal band, &c. Objective, Hart. 5. 

 Fig. 13. — Small part of peripharyngeal band, from specimen stained in osmic acid. Objective, 

 Hart. 7. 



Plate XIX. 

 Doliolum denticulatum, Quoy and Gaimard. 



Fig. 1. — Nerve ganglion and dorsal part of peripharyngeal band, from a specimen preserved 

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

 Hart. 4. 



Fig. 2. — The ends of some of the stigmata, from a specimen preserved in picric acid. Objective, 

 Swift, \ inch. 



Fig. 3. — Some of the ciliated cells bounding the stigmata, stained in picrocarmine. Objective, 

 Hart. 7. 



Fig. 4. — Some of the ciliated cells bounding the stigmata, stained with osmic acid. Objec- 

 tive, Zeiss, ^2, oil immersion. 



Fig. 5. — Some of the cells from the surface of the peripharyngeal band of a specimen pre- 

 served in chromic acid, and stained in picro-carmine. Objective, Zeiss, ■f s , oil 

 immersion. 



Fig. 6. — Part of the prebranchial zone in a specimen preserved in osmic acid and absolute 

 alcohol. Objective, Hart. 7. 



