PLATE XX. 



Figs. 1-6. Styela flava, Herdman. 

 Figs. 7-9. StyeJa dblonga, Herdman. 

 Figs. 10-13. Styela glans, Herdman. 



Fig. 1. Styela fiava, from the dorsal edge ; natural size. 



Fig. 2. A'sinall portion of the test of Styela Jlava,saxfa,ce view ; magnified (Hartn., obj. 4). 

 Fig. 3. A small portion of the mantle of StyeJa flam, .showing the musculature: 

 magnified (Hartn., obj. 4). 

 Part of the branchial sac of StyeJa flava, showing a fold (br.f.), seen from the 



inside; magnified (Hartn., obj. 4). 

 A small part of the dorsal lamina, showing the denticulations and ribs ; magnified 



(Hartn., obj. 4). 

 The dorsal region of the anterior end of the branchial sac, showing the dorsal 

 tubercle (d.t.), the peritubercular area, and part of the circle of tentacles 

 {tn., tu'. and tit".) ; magnified (Hartn., obj. 4). 

 Styela oblonga, from the right side ; natural size. 



Part of the branchial sac of Styela oblonga, showing a fold (brf.), seen from the 

 inside ; magnified (Hartn., obj. 4). 

 Fig. 9. A small portion of the last figure, much enlarged, to show the stigmatic cells 



(sg.c), and the muscular fibres (m.f.) (Zeiss., obj. } \). 

 Fig. 10. Styela glans, from the right side ; natural size. 

 Fig. 11. Part of the branchial sac of Stijela glans, seen from the inside; magnified 



(Hartn., obj. 4). 

 Fig. 12. A small portion of the last figure ; much enlarged (Hartn., obj. 5). 

 Fig. 13. The posterior end of the ventral edge of the branchial sac, seen from the inside^ 

 showing the posterior extremity of the endostyle, and its continuation round 

 the posterior end of the sac to join the end of the dorsal lamina ; magnified 

 (Hartn., obj. 4). 



