EXPLANATION OF PLATES. 133 



Fig. 11. Group of five individuals, of which three are very young, 



reduced. 



Fig. 12. Part of branchial sac. S. ^. 



Fig. 13. Dorsal languets. 



Fig. 14. Part of section of test, showing an ectodermal process. 



Fig. 15. Circle of tentacles and dorsal tubercle. 



Fig. 16. Another circle of tentacles, in which 12 are present. 



PLATE DIST. II. 



Fig. 1. Colony of Colella plicata, Herdm., nat. size. 



Fig. 2. Another colony, with much-convoluted Ascidiarium 



Fig. 3. Small colony, showing connection or junction at c. 



Fig. 4. Fan -shaped colony, showing delicate membrane between the 



branches. 

 Fig. 5. Small part of last, enlarged to show arrangement of Ascidio- 



zooids. 



Fig. 6. Colony, showing junction at c. 

 Fig. 7. Two colonies, with distinct bases, joined at c. 

 Fig. 8. Small colony, with long, slender peduncle. 

 Fig. 9. Piece of small colony, showing two connections at c. 

 Fig. 10. Very irregular colony. 

 Fig. 11. Small massive colony. 

 Fig. 12. An Ascidiozooid of C. plicata, measuring 2 mm. in length and 



- 5 mm. in breadth. S. 1. 

 Fig. 13. Part of section through peduncle, showing test and ectodermal 



vascular appendages, v. 

 Fig. 14. Part of section of test, showing bladder cells and pigment 



cells. S. i 

 Fig. 15. Part of branchial sac, with dorsal languets. 



PLATE DIST. III. 



Fig. 1. Group of colonies of Colella claviformis, Herdrn. 



Fig. 2. Another colony of unusual shape. 



Fig. 3. Another colony, with Ascidiozooids more distinct. 



Fig. 4. A colony in median, vertical section. 



Fig. 5. Section of the test. 



Fig. 6. Section of test of another colony, where yellow pigment cells 



are more abundant. 



Fig. 7. Outline of long, slender Ascidiozooid, 5 mm. in length. 



