234 



PAYNE BK4ELOW ON 



oe. t. oesopliageal lube, or canal. 



os. osculum. 



ot. rhopalial concretion (otolith). 



p. proboscis. 



p p. pillar of the proboscis. 



r c. radial canal. 



rh. rh opal him. 



rh. c. rhopalial canal. 



rh. t. rhopalial tentacle. 



s. stem. 



s e. sensory epithelium. 



sep. septum. 



s f. septal funnel. 



s <;. subgeiiital cavity. 



s ui. septal muscle. 



s u. subuuibrella. 



t. tentacle. 



v. vesicle. 



za. brownish green cells, symbiotic algae. 



PLATE 31. 



Fig. 1. Portion of the calyx and stem of a scyphistoma with a fully developed bud (b) attached. A, the outline of the 

 same bud when contracted. 



Fig. 2. Similar to the preceding, except for the formation of a second bud (/i') which bears the older one (ft) upon its 

 apex, 



Fig. 3. The form of the plauula-like bud during the first two days alter becoming free. A, B, and C, are the successive 

 changes in shape observed in one specimen during a few minutes. Tlie arrows show the direction in which it swims. 



Fig. 4. Larva of probably the third day. A, lateral aspect; B, oral aspect. 



Fig. 5. A larva of abmit the same age, 48 hours or over. 



Fig. li. Another larva of 48 hours or over. 



Fig. 7. Larva of the fourth day. 



Fig. 8. Free scyphistoma of the fifth day, with rudiments of four tentacles. The arrows show the direction of progres- 

 sion and rotation. 



Fig. 0. A scyphistoma of about the same age, with the rudiments of eight tentacles. 



Fig. 10. Oral aspect of ?i similar larva, perhaps somewhat younger. 



Fig. 11. A scyphistoma a little more advanced, probably in the fifth day. 



Fig. 12. A still more advanced seyphistoma of the fifth day. The four tentacles first formed are much longer than the 

 other four. 



Fig. I-'.. Scyphistoiiri of the sixth day, attached, and with eight tentacles. 



Fig. 14. Scyphistoma with rudiments of the second set of eight tentacles. Two tentacles of the first series are bifur- 

 cated 



Fig. l"i. Scyphistoma with sixteen tentacles fully developed, in the attitude of feeding. 



Fig. Hi. Oral aspect of a similar specimen. 



PLATE ;te. 



Fiu. 17. Scyphistoma showing first truces of rhopalial structure. 



Fit;. IK. A small portion of the margin more highly magnified. 



Fig. l!i. Scyphistoma at a slightly older stage. 



l-'iu. i'o. Small part of the margin of a similar larva. 



Fig. 21. An early stage in strobilization. 



Fig. '2'2. A rhopalial tentacle of the same specimen seen from the side. 



Fig. '2'.',. An oliler rhopalial tentacle. 



Fit;. '_'l. Strobila in which the rhopalial tentacles have begun to degenerate. 



