172 SCIENCE PROGRESS. 



between two distinguished German naturalists, as to the 

 systematic position of the Scyphomedusae. No one who 

 has studied this group at all carefully can doubt for a 

 moment the justification of the step that was taken by 

 the older naturalists in separating the " covered-eyed ' 

 medusse from the "naked-eyed". In many anatomical 

 characters, such as the absence of a velum, the endodermic 

 origin of the gonads, the presence of gastral filaments, 

 and the structure of the sensory bodies, the covered- 

 eyed medusse, or Scyphomedusae as they are now called, 

 are widely separated from the naked-eyed medusae, or 

 Hydromedusse. But to remove them from the Hydrozoa 

 altogether, as Goette wishes us to do, and place them in 

 the class Anthozoa, is a step which cannot be taken with- 

 out very careful consideration of the facts of anatomy and 

 development. 



The main point upon which the whole controversy turns 

 is the presence or absence of an ectodermic invagination in 

 the developing larva which forms the lining epithelium of 

 the manubrium and a part of the gastric cavity. Unfortu- 

 nately, upon this point we find very divergent statements. 



Claus 1 has recently published a paper in which he 

 maintains that the inner lining of the manubrium of the 

 Scyphomedusae is not formed from the ectoderm at all 

 but from the endoderm. He carefully reinvestigated the 

 development of the two genera Chrysaora and Coty- 

 lorhiza at the zoological station at Trieste, and found 

 that the place where the ectoderm and the endoderm join 

 is the edge of the mouth. From this it follows that the 

 gonads, the gastral filaments, and the epithelium of all 

 the gastric pouches are of endodermic origin, and there 

 is nothing in the structure of the Scyphomedusan which 

 corresponds with the stomodaeum of the Anthozoa. The 

 temporary ectodermic invagination which takes place at 

 the distal pole after the free swimming gastrula embryo 

 comes to rest is again evaginated to form the proboscis 



1 Claus, C., Ueber die Entwickelung des Scyphostoma von Coty- 

 lorhiza Aurelia, und Chrysaora, Arb. z. Inst. Wien., x. 



