TRID AC N A. 



Plate VIII. 



Species 8. (Fig. a, b, Mus. Cuming.) 



Tridacna ferruginea. Trid. testa mboblongo-ovatd, 

 quinqve-costata, costis parum elevatis, ad latera mb- 

 obsoletis, dense sqiiamato-serratis, interstitiis trilira- 

 fis; sordide alhil, versus marginem ferrngineo tinctd. 



The rust-stained Tridacna. Shell rather oblong- 

 ovate, five-ribbed, ribs but little raised, almost obso- 

 lete at the sides, densely scale-serrated, interstices 

 two- to three-ridged ; dead white, rust-stained to- 

 wards the margin. 



Hab. ? 



This appears to me to be very generally distinguished 

 from T. crocea, to which it is the nearest allied, by its more 

 oblong form and rust-brown colouring. The same dis- 

 tinctions of character may be observed in young speci- 

 mens of the respective species as given at Fig. 8 b and 9 a. 



Species 9. (Fig. a, b, Mus. Cuming.) 



Tridacna crocea. Trid. testa late ovatd, versus umbones 

 gibbosiusculd, quinqne-costntd, costis parum elevatis, 

 dense squamato-serratis, interstitiis subobscure trilira- 

 tis ; albidd, croceo-ruhente tincln et concentrice undatd. 



The saffron Tridacna. Shell broadly ovate, rather 

 gibbose towards the umboes, five-ribbed, ribs but 

 little elevated, densely scale-sen-ated, interstices ra- 

 ther obscurely three-ridged ; whitish, stained and 

 concentrically waved with saifron-red. 



Lamarck, Anira. sans vert. vol. vii. p. 10. 



Hab. Philippine Islands ; Cuming. 



In consequence of the lunule of this species gaping 

 more largely than usual, the shell is very gibbous about 

 the umboes, and attenuately pinched at the margin. The 

 ribs are but superficially developed, and the scales are 

 merely stunted imbrications. 



June, 1863. 



