s. g. subgenital cavity 



s. m. septal muscle 



s. u. subiimbrella 



t. tentacle 



V. vesicle 



Fig. 1. A scyphistoma in the process of budding. In 

 this case a second bud (b,,) has formed before the first (b,) 

 is set free. 



Figs. 2a, b, and c. A planula-like larva showing the 

 changes of shape assumed by one specimen dulling a few minutes. 

 The arrov/ shows direction of motion. 



Fig. 3a. A larva in which the moutii has just formed. 



Fig. 3b. Oral aspect of the same specimen. 



Figs. 4a and b. A slightly older specimen viewed in two 

 planes at right angles to one another. 



Fig. 5 Larva with first traces of the proboscis and cir- 

 cumoral disk. 



Fig. 6. Scyphistoma very recently attached. 



Fig. 7. Oral aspect of a similar larva. 



Fig. 8. A scyphistoma with rudiments of eight tentacles 

 but still swimming freely. 



74 



