138 ZOOLOGICAL PHILOSOPHY 



Observations. 



This is the third main hne of demarcation which has to be drawn 

 in the natural classification of animals. 



We here find altogether new forms which, however, belong in general 

 to one type, viz. the radiating arrangement of the parts both internal 

 and external. 



We have no longer to deal with animals with elongated bodies, 

 a superior terminal mouth, usually fixed in a polypary, and living 

 together in great numbers which share a common Hfe, but we have to 

 deal with animals whose organisation is more complex than that of the 

 polyps and which are not compound but always free, which have a 

 conformation pecuhar to themselves and assume in general the 

 inverted position. 



Nearly all the radiarians have tubes which draw in water and appear 

 to be water-bearing tracheae, and in a great many of them are found 

 peculiar bodies resembling ovaries. 



From a memoir which I lately heard read at a meeting of the 

 professors of the Museum, I learn that a skilful observer, Dr. Spix, a 

 Bavarian doctor, has discovered the apparatus of a nervous system in 

 star-fishes and sea-anemones. 



Dr. Spix affirms that he has seen in the red star-fish, under a tendinous 

 membrane which is suspended over the stomach hke a tent, a plexus 

 consisting of whitish nodules and threads, and in addition, at the origin 

 of each arm, two nodules or ganglia communicating together by a 

 thread and giving rise to other threads which go to the neighbouring 

 parts. Among these are two very long ones which traverse the entire 

 length of the arm and send out branches to the tentacles.^ 



According to the observations of this savant there are in each arm 

 two nodules, a short prolongation of the stomach (caecum), two hepatic 

 lobes, two ovaries and tracheal canals. 



In sea-anemones Dr. Spix observed at the base of these animals 

 below the stomach several pairs of nodules arranged about a centre 

 and communicating together by cylindrical threads. These give rise 

 to others which pass to the upper parts : he found moreover four 

 ovaries surrounding the stomach, from the base of which issue canals 

 which unite together and open at a point within the ahmentary 

 cavity. 



It is surprising that the apparatus of such compUcated organs should 

 have escaped the notice of all those who have studied the organisation 

 of these animals. 



If Dr. Spix is correct in what he describes ; if he is not mistaken by 

 1 [Tube-feet. H. E.] 



