400 POLYPI. 



[Subkingdom Radiata.] 



The Red-Piped Coral [Tubipora musica, Linn.]. 



This coral appears to be an aggregate of different animals, but there 

 seems to be a connected principle that runs through the whole. 



A piece of piped coral consists of tubes of various numbers, three or 

 four inches long, mostly arising from one base, and they go from it in 

 a radiated manner. Each tube is about y^th of an inch in diameter, 

 but not so much in the bore. 



As they go from the base in a radiated manner, they ought to become 

 at some distance from one another, at their mouths or terminations ; 

 but, where they become at some distance, a new one forms in this 

 interstice like the branch of a tree : so that they are nearly as close to 

 each other at their terminations or mouths as at the bottom. They are 

 attached laterally to each other by several cross-bars or unions, about 

 an inch from each other, so that they all support each other. These 

 lateral attachments are pretty regularly formed, running across, nearly 

 in the same place, through the whole. The substance of these is bone ; 

 that is, it is composed of animal substance and calcareous earth inter- 

 mixed; either of which may be extracted without hurting the other 1 . 



Each pipe is lined through its whole length with a very thin animal 

 substance, a continuation from the animal which may be said to be 

 striped or ridged on its inside in a longitudinal direction. 



Just within the mouth of the pipe is the body of the animal, which 

 is composed of very few parts. The basis of tbis animal is attached to 

 the sides of the lining of the tube by, we may suppose, a muscular 

 attachment to pull the animal in when it is protruded. There is a very 

 thin membrane, which encloses the animal and its tentacles, when these 

 are drawn into the shell or tube, but which allows the animal to pro- 

 trude through it, and acts as a prepuce. 



The tentacula are four ; two seem to be smaller than the other two, 

 and almost form the larger part of the animal. They are firm, and 

 seemed to be feathered on their whole inner surface : as far as I could 

 judge, they looked like four pennse marinae joined by their stalks. They 

 are of a yellow colour, and when drawn in, are all laid parallel to 

 each other. In the centre of these is the mouth, which leads into 

 the stomach: this viscus is a blind pouch 2 . 



1 [Hunt, Preps. Phys. Series, Kos. 83, 84, 85. This beautiful coral is from the 

 coast of Australia, and was probably given to Hunter by Sir Joseph Banks.] 



2 [lb. No. 421.] 



