120 ACALEPH.E OF THE GREEKS. 



ultra-marine. These suckers surround a central 

 mouth, to which doubtless they serve to convey 

 the animal's food. It floats in the sea, like 

 other acalephse, and its habits are probably 

 similar to those of the Cephea, which, though 

 it has no internal skeleton, approaches the Por- 

 pita in many points of structure. The Velella 

 resembles the Porpita, but has a little sail 

 of cartilaginous membrane elevated on its disk, 

 like a gnomon on a dial -plate. It also is an 

 inhabitant of the Lycian sea. 



The ancient Greeks included under the name 

 of Acalephce both the Medusa and the Actinea ; 

 and indeed they closely approach in organization. 

 When, however, we are told by Aristotle, after 

 he has distinctly described the common rock- 

 inhabiting Actinece, that there is a kind which 

 detaches itself at night from the rocks and 

 goes out swimming to seek for its prey, we must 

 not suppose (as has been hitherto conjectured) 

 that he confounded the two animals — the float- 

 ing Medusa and the fixed Actinea — and had mis- 

 taken the former for a state of the latter. In 

 the Greek seas, and especially on the coast of 

 Lycia there are true Actinece, which are equally 

 at home fixed to the rock and swimming about 



