\ KKVISIuN I.I' IIIK AI'SIKM.IA\ TKIhACVA IIK|.|.KV. IC'I 



'riie (liaii^ ('lani is a pniispiVnmis limine (ni tlio oiiMyiiio' roefs of tlio 

 CJrent. Bari'ier. Even yef there is sonu' iiiitei'taint y iibont its syiHuiyim 

 and (leveliipjuent. It is possible tliiit two or move species distinct in ymitli 

 may oonveig'e in age till tliey are alike tliant Clams. 



I n aged individuals,' the cardinal teeth increase dis[ij'opoi'l iojiately, 

 rlie latei'als tend to atrophy, the pedal oritice closes and the external 

 sculpture of the valve hecomes obliterated. Wheii the characters whicdi 

 distinguish smallei- shells from each other, thus disappear in scnilit\, 

 recognition of tlie earlier stages of the Ciiant (Main depends on ti'acing the 

 species backwards through a series of young and younger individuals. 

 On analysis the tii'st point is that the Giant Clam is a perching and not a 

 boring form, secondly, the I'ibs at the margin have the scales nu)re crowded 

 than in 7'. .•^iiniinnisu, thirdly, the Giant (Mam is more inequilateral than 

 are 7'. niiitica or 7'. ^i[Hiiiinixii . Fi'om these, 1 conclude that the Giant 

 Clam is the adult of what is generally known as 7'. nidis, Reeve, but 

 wliieli was earlier named T. imnp bv Rolten. In his original introduction 

 of the Tiame, Tiinne cited a figui'e of 7'. mha- from Argenville (Conchvlio- 

 logie, '2 ed., 17.")7, pi. xxiii., tig. e). 



Of what is now the genus I'riildfini, Linnc perceived only a single 

 species, his ('Ikiiuh (liijus. The accepted usage of the name Tridid-mi qli/ng 

 was unchallenged until Hanley I'eported that one of two sj^ecimens in the 

 Linnean private collection was 7'. ■•<ijiii(iii(i.-<ii, and the subsequent redescrip- 

 tion of the Museum Ulricae best suited the same species. But, on the 

 contrary, the Linnean specimen of T. ftpiKuiosii cannot be considei'ed a type ; 

 wliereas the shell in the Royal Museum noted in the original description 

 as weighing 532 pounds, has every claim to be the Linnean type, which is 

 perhaps still extant at Uppsala. Granting this, Lamarck may be endowed 

 with the authoiity of the first reviser in dealing with the Ijinnean complex, 

 and his separation of 7'. sqimmoi^u from T. iji'jits appi'oved as a cori-ect 

 piocednre. 



Captain Flindei's when on a voyage of discoverv in Toi'i'es Straits in 

 1802, made the following observations: — " There being no water' (ui the 

 Island (Half-way Island), they (the Indians) seem to have liir upon the 

 following expedient to obtain it : Long slips of bark ar-e tied round the 

 smooth stems of the pandaniis, and the loose ends are led into the shells 

 of the cockle fCliitnni ij'nj.ts), placed undpr'neath. By these slips, the rain 

 which r'uns down the branches and stem of the ti'ee, is conducted into the 

 shells, and fills them at every consider'able shower; and as each shell will 

 contain two ov thr-ee pints, foi-ty or- fifty thus placed under- different trees 

 will suppi}'. a good number of men. A pair- of these cockle shells, bh-ai-ht'd 

 in the sun, weighed a hundred and one pounds ; but still thev were much 

 infer-ior in size to some I have since seen."'' 



■' It was su.v..rf..sted by Filaiiivilli- (Diet. Sei. Nat., Iv., 1828, p. 256) that with 

 advaneini>- a^-e tlie animal iv.isf'd tu aillu'ii- to iIih rock and the by.s.sal gape closed. 



^ FHuders— Voy. T.nr. .\ustr., ii., L814, p. lU. 



