EXPLANATION OF REFERENCE LETTERS ON PLATES. 



a. Anus. 



b. Endostyle. 



c. Membranoblasts. 



d. (Esophagus. 



e. Pharynx. 

 /. Mouth. 

 g. Stomach. 



/i. Right lobe of stomach. 

 i. Left lobe of stomach. 

 /. The large cells that cover more than half the 



body. 



k. Right gill. 

 /. Left gill. 



m. Reproductive organ. 

 n. Gelatinous mass. 

 o. Parasites. 



p. Openings through which the currents of 

 water enter the house. 



q. Opening through which the water is dis- 

 charged, and the animal escapes when it 

 leaves the house. 



f- Egg. 



s. Embryo. 



t. Branchial pouches of pharynx. 



u. Spiracles. 



v. Stomach ( ?) of embryo. 



w. Chorda (?) of embryo. 



.r. Root-like process from the body of the em- 

 bryo, embedded in the tail of the adult. 



31. Internal or branchial spiracle, through which, 

 the branchial pouch of the pharynx opens. 



s. Follicle cells. 



ab. Part of tail of adult. 



ac. External opening of spiracle. 



ad. The median oral division of the pharynx, 



showing its communication with the two 

 branchial pouches, *. t. 



EXPLANATION OF PLATES. 



PLATE i. 



FIG. i. Salpa florida, solitary form, dorsal view of adult. 



FIG. 2. Salpa florida, solitary form, ventral view of adult. 



FIG. 3. Salpa florida, solitary form, digestive organs of adult. 



FIG. 4. Salpa florida, solitary form, ventral view of young 4.5 mm. long. 



FIG. 5. Salpa floridana, aggregated form, side view ; 



FIG. 6. Salpa floridana, aggregated form, ventral view. 



PLATE 2. 



FIG. 7. Salpa floridana, solitary form, side view of very young embryo. 

 FIG. 8. Salpa pinnata, aggregated form. 

 FIG. 9. Salpa floridana, aggregated form, dorsal view of colony. 



PLATES 3 TO 8. 

 All figures on plates 3 to 8 refer to Oiko pleura tortugensis nov. sp. 



PLATE 3. 



FIG. i. Side view of body of Oiko pleura tortugensis. 



FIGS. 4 and 5. Views of the house. 



FIG. 6. Gregarina-like parasites in the house. 



PLATE 4. 



FIG. 2. Ventral view of body of adult. 



FIG. 3. Dorsal view. 



FIG. ii. Side view of entire adult animal. 



FIG. 12. Rhizopod Gromia rooted to the tail of Oikopleura. 



PLATES 5 AND 6. 

 FIGS. 7, 8, 9, 10. Digestive and reproductive organs of adult. 



PLATE 7. 



FIG. 13. Part of tail, magnified 13 diameters, showing eggs and embryos rooted as 



parasites upon it. 



FIG. 14. Ventral view of embryo magnified 300 diameters. 

 FIG. 15. Dorsal view of the embryo shown in figure 14. 

 FIG. 16. Egg within its follicle, attached to the tail. 

 FIGS. 19 and 20. Views of an embryo younger than the one shown in figures 14 and 15. 



PLATE 8. 



FIGS. 17 and 18. Views of the embryo shown in figures 19 and 20, plate 7. 



FIGS. 21 to 25. Sections of the embryo shown in figures 14 and 15, plate 7. Figure 

 23 most anterior section. Figures 24 and 25, sections of the root of attach- 

 ment imbedded within the tissues of the tail of Oikopleura tortugensis. 



94 



