CHAPTER XXXI: THE FILE SHELLS 



Family Limid^ 

 Genus LIMA, Brug. 



Shell obliquely oval, eared, white, gaping at the sides; 

 hinge toothless, with triangular ligament pit; umbones well 

 apart; surface sculptured with radiating ridges bearing numerous 

 imbricated, spiny points ; mantle inflated, bag-like, open, fringed 

 at border, set with eyes; foot fmger-like; gills 4, equal on each 

 side, distinct. A large family, mostly extinct. 



The roughened surfaces of all these white shells suggest 

 that they might serve as rasping tools. The scoop shape is 

 constant. The depth of the shells is variable. Chiefly 

 inhabitants of the Red Sea and Mediterranean, yet a few 

 species are scattered in the East and West Indies, Australia and 

 Northern Europe. 



In more ways than a few the file shells resemble the scal- 

 lops. But they outdo them at many points. A school of young- 

 sters with shells like carved ivory, flit through the water, zigzag- 

 ging with all the suddenness and swiftness of the scallops, but 

 they go hinge foremost, and trail after them a graceful and 

 copious sheaf of long mantle tentacles. They often throw these 

 about each other, and thus adhering, swim by twos and threes. 

 Drawn in, these fringes are rigid horns guarding the gaping valves. 

 Dr. Jeffreys had a Lima in his aquarium which clasped his fmger 

 with its tentacles. He drew it about for awhile, then attempted 

 to shake it off, but failed. He had to tear several filaments from 

 the mantle ; and even then, they continued to writhe and cling 

 as if alive and determined to hold on. They were removed with 

 considerable difficulty. 



When free life palls, the Lima can attach itself by a byssus. 

 This is detachable at will. Many prefer to remain stationary, 

 so they build about their shells a web of byssal threads, plastered 

 with slime in which fragments of shells, seaweeds, coral, and 



408 



