PLATE XXVII. 



Abysaasei-dia wyvillii, Herdmaii. 



Fig. 1. Abyssascidia wyvillii, from the upper or dorsal surface ; natural size. 



Fig. 2. The same, from the lower or ventral surface ; natural size. 



Fig. 3. The same, with the test removed ; seen from the right side, showing the mantle. 



with muscular bands, the alimentary canal, and the atrial siphon ; natural size. 

 Fig. 4. The same, from the left side, showing the muscular bands in the mantle and the 



branchial siphon ; natural size. 

 The viscera, seen from the right side, showing the alimentary canal and the 



genital mass ; enlarged. 

 The same, from the left side ; enlarged. 



Part of the branchial sac, seen from the inside ; magnified (Hartn., obj. 5). 

 A small portion of the preceding figure ; greatly enlarged (Hartn., obj. 7). 

 Part of an internal longitudinal bar, from fig. 7, showing the junction with a 



connecting duct (c.d.) ; greatly enlarged (Hartn., obj. 7). 

 Fig. 10. Epithelial cells from the surface of a horizontal membrane of the branchial sac ; 



much magnified (Hartn., obj. 10). 

 Fig. 11. Part of the series of dorsal languets ; magnified (Hartn., obj. 4). 

 Fig. 1 2. Anterior extremity of the endostyle (en.), and part of the tentacular circlet (tn.) ; 



magnified (Hartn.,- obj. 4). 

 Fig. 13. Another part of the tentacular circlet; magnified (Hartn., obj. 4). 

 Fig. 14. The dorsal tubercle and peripharyngeal bands; magnified (Hartn., obj. 4). 

 Fig. 15. The nerve ganglion; magnified (Hartn., obj. 4). 

 Fig. 16. Part of the edge of the genital mass, showing testicular vesicles (t.v.), and ova 



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

 Fig. 17. Some of the ova; much magnified (Hartn., obj. 7). 

 Fig. 18. Two testicular vesicles ; much magnified (Hartn., ol >j. 7). 



