372 



BRACHIOPODA 



[CH. 



groove is lined with cilia and so is the inner face of each tentacle. 

 The whole of this apparatus is called the lophoph ore. It might be 

 described as a ring of tentacles, the ends of which are drawn out so 

 as to form the arms. It is never quite so simple as the above 

 account would lead one to suppose, for the ring is often produced 

 into two minor lobes forming the lesser arms situated between the 

 main ones, and in many genera the two main arms are raised up 

 from the level of the body- wall and each is twisted into a spiral. 

 The dorsal shell may be prolonged into a series of plates and even 

 into elaborate bands and loops which serve to support such lopho- 

 phores. 



FIG. 175. View of the inner side of the right half of Waldheimta aiistralis. 

 From a dissection by J. J. Lister. 



1. Mouth. 2. Lophophore. 3. Stomach. 4. Liver tubes. 5. Median 



ridge on dorsal shell. 6. Heart. 7. Intestine, ending blindly. 



8. Muscle from dorsal valve of shell to stalk. 9. Internal funnel-shaped 



' opening of kidney. 10. Stalk. 11. Body- wall. 12. Tentacles. 



13. Coil of lip. 14. Terminal tentacles. 



The mouth lies on the middle line at the bottom of the gutter 



between the lip in front and the tentacles behind. 



struct*. 1 r ^ n lophophore is thus an organ for catching food and 



passing it into the mouth. The cilia which cover the 



inner surface of the tentacles and line the gutter set ujx small 



whirlpools in the water so that minute animals and algae becoming 



involved in these are swept into the mouth. In many species the 



