Tridacna is distinguished from Hippopus by the large opening in the hinge.
The former is supposed to have originated from the Tridacna shell, the latter from the taro.
Arched or vaulted, as the exfoliations on the cost of Tridacna Elongata, fig. 157.
The shell of the Tridacna gigas is the largest anywhere known.
A few are fashioned out of the thick portion of the shell of Tridacna gigas.
The valves of Tridacna gigas are sometimes found a yard and a half in length, and weighing five hundred pounds.
The Linnan genus Chama, included the beautiful shells now called Tridacna.
Tridacna safrana is of a beautiful blue round the edges, rayed through a shade of very pale blue.
I did not know the name at the time, but I afterwards learned that it must have been a specimen of the Tridacna gigas.
The accompanying representations of Tridacna squamosa (Figs. 149 and 150) will convey a general idea of the genus.