398 Trajisactions. 



EXPLANATION OF TEXT-BLOCKS. 



One segment of the capitulura. 

 Musculature of a mesentery. 



Diagrammatic representation of portion of cross-section of 

 a tentacle. 



Fig. 5. Actinia tenebrosa. Diagram showing manner of division of mesenteric filament 

 into three branches. 



Fig. 6. Sagartia nutrix. Young attached to body-wall. Animal expanded. 



Fig. 7. Thoe albida. Diagram to show manner of deposit of pigment round bases of 

 tentacles. 



Fig. 8. Thoe albida. Portion of an acontium. (From a rough slide — diagrammatic.) 

 Tlie nerve-cells appear to be on one side, the nematocysts on the other. 



Fig. 9. Paractis ferax. Part of a cross-section of body-wall to show the characteristic 

 thinning of the mesogloea at intervals. 



Fig. LO. Paractis ferax. Showing forking of the mesogloea in the body-wall. 



Fig. 11. ,, A mesentery in cross-section, sliowing parietal muscle, retrac- 



tor muscle, ova, and mesenterial filament. 



Fig. 12. Corynactis haddoni. Diagrams to illustrate the steps in lateral fission. 



EXPLANATION OF PLATES XXI-XXVIII. 



Plate XXI. 

 Fig. 1. Sagartia nutrix photograph on a piece of seaweed. Animal partly contracted. 

 Fig. 2. ,, Cross-section of sphincter. 



Plate XXII. 



Fig. 1. Edwardsia tricolor. Part of a cross-section, showing some of the mesenteries 



and ova in the body-cavity ; x 50. 

 Fig. 2. Edwardsia tricolor. Longitudinal section of capitulum, showing ova in stomo- 



dseum. 



Plate XXIII. 



Fig. 1. Actinia tenebrosa. Part of a cross-section, showing one pair of directives and 

 one siphonoglyph ; also, unequal development of mesenteries. On the 

 right— Dirs. III. II, III, I ; on the left— Dirs. Ill, II, III, II, III, I. 



Note. — The junctions of the two ])airs of ]irimaries with the stomo- 

 dseura do not show clearly in the micrograpli. though tliey were clear 

 enough in the preparation. 



Fig. 2. Actinia tenebrosa. " Trefoil " of mesenteric filament. 



Plate XXIV. 



Fie. 1. Paractis ferax. Part of a cross - section, showing a mesentery with ova in an 

 advanced stage. 



F'g. 2. Tealidium cinctum. Part of a cross-section, showing directives and other mesen- 

 teries, and part of siphonoglyph. 



Plate XXV. 



Fig. 1. Cradactis plicatus. Cross-section of spliincter. 



Fig. 2. ,, Part of a cross-section, showing directives and other mesen- 



teries, and one siphonoglyph. 



Plate XXVI. 



Fig. 1. Phhjctenactis retifera. Cross-section of tentacle, showing reticular structure of 



the mesogloea. CJreatly magnified. 

 Fig. 2. Portion of the same, more highly magnified. 



Plate XXVII. 



Fig. 1. Phlyctenactis morrisovii. Portion of a longitudinal section, showing body- 

 wall, ova, and one vesicle. 



Fig. 2. Sagartia vagrans. Part of a cross-section, showing directives and other mesen- 

 teries, and part of stomodanim. 



Plate XXVIII. 

 Paractis ferax. Section below the stomodaeum, showing mesenteries, witli ova and 

 mesenterial filaments ; also masses of ova between the mesenteries. 



