BRACHIOPODA. 107 



membrane, the mantle, which is divided into two lobes, 

 one occurring in each valve, and the space between the 

 two is known as the pallial chamber. The margin of the 

 mantle is thickened and carries numerous chitinous setae 

 The alimentary canal is placed in a portion of the body- 

 cavity (coelom) in the posterior part of the shell; the 

 mouth (fig. 29, v) opens into the pallial chamber, and 

 leads into an oesophagus which is followed by a stomach 



FIG. 29. Waldheimiajlavescem, Recent. Longitudinal section, d, arms; 

 h, cirri; a, adductor muscle; c, c', divaricator muscles; ss, septum; 

 r, mouth ; z, terminal part of alimentary canal. (After Davidson.) 



surrounded by liver-lobes, and an intestine ; in the articu- 

 late brachiopods the latter is short and ends blindly, in 

 the inarticulate it is long and ends in an anus which opens 

 into the pallial chamber. The nervous system consists of 

 a ring round the oesophagus, with ganglionic enlargements 

 from which nerves are given off to the arms, mantle, etc. 

 The part of the body-cavity which surrounds the alimentary 

 canal communicates with the pallial chamber by means 

 of two or four funnel-shaped canals. The body-cavity 



