74 



SHELL GALLEKY. 



Small 

 Table- 

 Case A 

 against 

 the west 

 wall to left 

 of main 

 entrance.* 



BRACHIOPODA. 



The Brachiopoda, though presenting a certain outward resemblance 

 to bivalved Mollusca, are quite distinct from this group. They are 

 all marine, and all possess a bivalve shell. They grow attached to 

 rocks (Fig. 1), usually by a horny peduncle or stalk passing between 

 the two valves, or through a foramen in one of the latter ; or, 

 peduncle and foramen may be absent, one of the valves adhering by 



Fig. 1. 



British Brachiopods {Terebratula and Crania). 



its surface to the rocks ; some species of Lingula live in tubes in the 

 sand, or mud. They occur at all depths, from shallow^ water up to 

 2900 fathoms, but the largest number of species live at a depth of 

 about 350 fathoms. Though found in all seas, the localities whence 

 they have been obtained are comparatively few in number ; but 

 specimens are usually congregated in considerable numbers, in places 

 where they do occur. The surviving species of Brachiopods con- 



* The Davidson Collection of Recent Brachiopoda is placed along with the 

 Fossil forms in the Geological Section. 



