5o A Guide to the Zoological Collections in the 



worms, near which, however, they are classed on embryolo- 

 gical grounds. 



The Brachiopod shell consists of an upper or dorsal 

 and a lower or ventral valve, and, as may be observed in the 

 specimens of Lingula anatina, is furnished at its hinder 

 end with a long fleshy stalk, or " peduncle ", by which the 

 animal is fixed to the sea-bottom. In Lingula the ''pedun- 

 cle " simply passes out between the valves : in Waldhei- 

 mia it passes through an aperture in the beak of the ven- 

 tral shell. In a few forms the "peduncle" is wanting. 



A general idea of the internal organisation of the Bra^ 

 chiopoda may be gained by a study of the lettered dissec- 

 tions of Lingula anatina. In Lingula the inner surface 

 of each valve is seen to be lined by a thickened fold 

 of the integument — the " mantle '\ the edge of the mantle 

 lobes being closely fringed with "setae". A large part 

 of the space between the "mantle" folds is occupied 

 by the coils of two long fringed " arms " — one situated 

 on each side of the mouth — which function both for 

 procuring food and as organs of respiration. At the 

 broad fore-end of the shell is the mouth lying between the 

 coiled up arms, and behind it the coiled intestine, embedded 

 in a dark brown granular mass, — the liver. The rest of the 

 cavity is filled by the great muscles which open and close 

 the shell. 



The Brachiopoda are all marine : they are but sparely 

 represented at the present day, the majority of known 

 species being fossils, many of them of great geological 

 antiquity. 



The Brachiopoda are divided into two groups — the 

 Ecardines^ represented by Lingula^ in which the shell is 

 not hinged and not furnished with an internal calcareous 

 hoop for the support of the long coiled " arms ", and the 

 Testicardines, represented by Waldheimia, in which the 

 shell is hinged and furnished with an internal calcareous 

 hoop for the support of the " arms ". 



In the collection the only representatives from the 

 Indian seas are Lingula and Crania from comparatively 



