" SHELLS " 313 



scription. The mollusc lies buried in sand, and never leaves its burrow except 

 on compulsion by a pinch of salt or the spade of a bait-seeking fisherman. 

 The species with straight edges is the Pod Razor (S. siliqua). 



17. The Sabre Razor (S. ensis) has a curved outline and is smaller. 



18. The Smooth Venus (Cytherea chione). There are a number of species 

 belonging to the Venus shells, but they are deep-sea inhabitants. This species, 

 however, is large enough to attract attention when it is washed up after a 

 storm on our southern or western coasts. It is 3 or 3^ inches across, white 

 inside, pale brown with a touch of pink outside, with lines of lighter colour 

 and darker radiating bands. 



19. The Smooth Artemis (Artemis Undo) and (20) the Rayed Artemis (Artemis 

 exoleta) are round shells with a slight indentation at the beak, thick and heavy, 

 the latter with fine concentric ridges and rays of pinky brown, the former 

 smaller and smooth, frequently washed up in winter. 



21. The Tapes, or CARPET SHELLS, have usually beautiful patterns suggesting 

 tapestry or carpets. 



The Cross-cut Carpet Shell (Tapes decussata) is drab-coloured, with ridges 

 radiating from the beak, cross-cut by fine lines. 



22. The Golden Carpet Shell (Tapes aurea) is smaller, with shallow con- 

 centric lines, of a yellow or golden hue. 



23. The Comb Shell (Pectunculus glycimeris) is fairly common, and has 

 thick round valves about 2 inches long, smooth to the touch, but under the 

 pocket lens showing many fine lines from beak to rim. The colour is reddish, 

 set off by long sharp white wedges ; very variable. On the under side is a broad 

 flange with twenty-two teeth in two rows the comb, in fact, which gives the 

 shell its name. 



24. The Trough Shells are plentiful, and must be briefly typed by the 

 Rayed Trough Shell (Mactra stultorum], smooth, shaded brown, with a number 

 of white radiations. 



25. The Unrayed Trough Shell (M. luteola), as its name indicates, is similar, 

 but without the rays. 



26. The Otter Shells (Lutraria) are the largest British bivalves, some 

 5 inches long, not unlike Razor Shells, especially in their inability to close the 

 end of their shells. They live in mud, the commonest being L. elliptica. 



27. The Tellen Shells (Tellina) are delicate, flattened specimens, finely 

 grooved and with broad bands of pink. 



The Thick Tellen (T. crassa) is thick only in name, and has the pink bands 

 radiating from the beak, the interior being tinted pink or orange. All the 

 members of the genus burrow in sandy mud. 



