484 RECENT BRACHIOPODA chap. 



of his laboratory. The Lingtda place themselves A^ertically ; the 

 anterior end of the body just reaches the level of the sand ; the 

 three lobes into which the orifice of the tul^e is divided corre- 

 sponding with the three brushes of setae which project from the 

 anterior rim of the mantles. These setae are described by Morse 

 as projecting in the form of three funnels ; currents of water are 

 seen continually passing in at the side orifices and out through 

 the central. The tube consists of two portions : an upper part, 

 which is flattened to correspond with the flat shape of the body, 

 and a lower part, in which the stalk lies. The upper part 

 is lined with a layer of mucus, but the sand is not glued 

 together to form a definite tube. The lower part of the 

 stalk, or the whole when the animal is contracted, is lodged 

 in a definite tube composed of grains of sand agglutinated by 

 mucus, probably secreted from the walls of the stalk. At the 

 least sign of danger the stalk is contracted violently, and tlie 

 body is withdrawn to the bottom of the upper portion of the 

 tube. The rapid retreat of the animal is followed by the 

 collapse of the sand at the mouth of the tube, and all trace of 

 the presence of the Lingula is lost. 



The shells of this species are frequently rotated through a 

 small angle upon one another, a movement which is prevented 

 in the Testicardines by the hinge. In very young transparent 

 specimens Francois was able to observe the movements of the 

 fluid in the system of tubules which penetrate the mantle ; these 

 tubules are figured by him, and Fig. 315 is taken from his 

 illustration. 



Davidson, in his Monograph on the British Fossil Brachi- 

 opoda, states that the largest " recent Brachiopod which has 

 come under my notice is a specimen of Waldheimia venosa 

 Solander, measuring 3 inches 2 lines in length, by 2 inches in 

 breadth, and 1 inch 11 lines in depth." It was found in the 

 outer harbour of Fort William, Falkland Islands, in 1843. A 

 specimen of Terehratida grandis from the Tertiary deposits, how- 

 ever, exceeds this in all its dimensions. Its length was 4-| 

 inches, its breadth 3 inches 2 lines, and its depth 2 inches 2 

 lines. 



Distribution in Space 



Brachiopods are very localised ; they live in but few places 



