CHAPTER XIX: THE FURBELOWED CLAMS 



Family Tridacnid/e 



Shells equivalve, regular, truncated in front, very hard 

 and heavy; ligament external; valves strongly ribbed from the 

 hinge outward, ribs frilled, with wavy concentric laminae; hinge 

 with two interlocking teeth; mantle closed, but pedal opening 

 large; foot finger-like, with byssal groove; shell muscle large, 

 central. 



Genus TRIDACNA, Brug, 



The Tridacna or Furbelowed Clams, one of which, T. gigas, 

 is the largest of all mollusks, live in beds of some extent in lagunes 

 among coral reefs, among the islands of the Eastern and Pacific 

 seas. The shell is generally white, sometimes tinged with red 

 and saffron or brown-yellow, but the animal is brilliantly coloured. 

 M. Quoy describes the beautiful iridescent glare of blue, violet, 

 and yellow, variegated with fantastic markings, that is presented 

 by these sub-marine parterres as seen through the clear blue 

 water; and Mr. Cuming speaks with enthusiasm of passing over 

 a mass of them nearly a mile in extent,, which resembled nothing 

 so much as a beautiful bed of tulips. — Reeve. 



The Scaly Tridacna (T. squamosa, Lam.) has symmetri- 

 cal valves, its rounded ribs adorned with erected frills "that are 

 developed throughout with amplitude and precision." Fine can- 

 cellation adorns the grooves. The white substance of these 

 massive shells is tinged or concentrically streaked outside with 

 yellow or red. Diameter, 4 to 8 inches. 



Habitat. — Moluccas. 



The Giant Tridacna (T. gigas, Lam.) attains the enormous 

 weight of six to seven hundredweight, its massive bulk meas- 

 uring two to three feet across. One sees the single valves used 

 as henetiers at the doors of Catholic churches. The animals in- 

 habiting these gigantic shells weigh upward of twenty-five 

 pounds, and are described as very good to eat. The natives of 

 the Caroline Islands hew axe heads out of the thickest portions 



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