64 



1. Observations on the development of Gonionema indi- 

 cate that Haeckel's sharp distinctions between jelly- 

 fishes which he groups in his orders "Trachomedusae" 

 and "Leptomedusae" are not justified. 



2. Dehiscence occurs in Gonionema with precise perio- 

 dicity, and is definitely affected by changes in 

 light. 



3. Segmentation is total and equal; endoderm is formed 

 by delamination of the blastomeres; a solid morula 

 results. 



4. A planula stage occurs, and later a hydra stage, in 

 which the polyp develops first two tentacles, then 

 a second pair. 



5. Youngest medusae and oldest polyps show marked ho- 

 mologies; direct metamorphosis is suggested. 



6. Peculiar pathological phenomena appear, the larva 

 living for weeks in the form of a Plasmodium, with 

 amoebiform activities. 



