632 



THE POPULAR SCIENCE MONTHLY. 



— a true individual of a higher order. Here the transformation 

 of the colony to an individual is manifest. The Siphonophore is an 



animal with organs made up of 

 distinct animals, each having a 

 particular function. Elsewhere we 

 see these animal organs become 

 less and less independent. They 

 come together and arrange them- 

 selves around a central axis which 

 predominates, and end by forming 

 a being like the Porpita or Velelle, 

 which, but for the study of neigh- 

 boring types, would not be thought 

 of as a decomposable animal. 



At the present time most peo- 

 ple consider Sea-anemones (Fig. 9) 

 and Polyps, of the madrepores, 

 and coral, as simple organisms — 

 primitive individuals ; while to us 

 their origin is the same as that 

 of PorpitcE and Yelellm — the union 

 of three sorts of Hydroid Polyps. 

 The admirable researches of Mose- 

 ley on the Polyps of the family of 

 Stylasteridce furnish proof of this. 

 If we consider only their calcareous 

 parts, all these beings seem to be true Madrepores. The first doubt 

 concerning their true nature was raised by Agassiz, with reference to 

 the Millepores. 



;, Portngruese man-of-war (after Hux- 

 ley) ; b, VeleUa vulgaris (after Gosse). 



; b, Arachnaetis albida (after Gosse). 



Between a Coralarian and a Hydroid Polyp the difference is con- 

 siderable. One is a simple sac with tentacles, usually solid appendages 



