TRIDACNA AND HIPPOPDS. 181 



is nearly 15 inches long, and that in the Museum nearly as 

 large. 



4. scAPirA, f. 16, Meusch. fid. Adams. — Ovato-elongata, 

 flavida, radiatim leviter lirata, postice breviusculo, cuneato, 

 antice oblique producto obtuso, latissime hians ; costis 5-b 

 depressis, squamis tenuibus, augustis approximatis arcuatis 

 ornatis; interstitiis valide sulcatis. — Figures in the Enc. 

 Med. and Chemn. Conch, of this species, are referred to by 

 Lamarck for T. gif/as, to which it does not belong. It is too 

 ventricose and narrow, and not sufficiently cancellated to be 

 referred to crocea or ferrugiupa. The Messrs. Adams have 

 figured it in their ' Genera ' as Chamostrcea scapha of Meusch. 

 It has a very wide and long hiatus, with crenulated margins. 



5. CROCEA, f. 5, 6, 8, 9, 10, Lamk. — Ovata obliqua, pallide 

 aurantia vel ferruginea, liris radiantibus et rugis conceutricis 

 cancellata ; costis plus minusve depressis ; latere antico pro- 

 ducto, hiatu magno ; margine postico obtuse cuneato vel 

 rotundatim declivi ; costis plus minusve depressis, squamatis ; 

 squamis arcuatis angustis tenuibus, frequenter erosis. — Mr. 

 Reeve separated the variety with less sloping posterior side, 

 and more rusty colour, as T. ferruginea (f. 9), and also gave 

 the name ' Cumingii ' to another very beautiful variety (f. 8, 

 and perhaps f. 5), in which the ribs are a little more raised, 

 while the scales, better preserved and broader, are well set ofi' 

 by the bright colour of the intervals between the ribs. 



6. ELONGATA, f. 3, 4, LamaTch. — Oblonga, antice pro- 

 ducta, utrinque subacuminata, alba aut flavida costis 8-9 

 semirotundis la3viusculis ; squamis subdistantibus fornicatis 

 extantibus ; interstitiis costarum angustiusculis radiatim 

 liratis. — The distance and projection of the vaulted scales, 

 the smoothness of the ribs, and narrowness of the strongly 

 ridged interstices, distinguish all the specimens we have seen 

 of this species from T. ferruginea, in our last plate (f. 16), 

 and it is known from T. lanceolata, (f. 18) by other characters. 



7. LANCEOLATA, f. 19, Sowcrby. — Oblonga, acuminata, 

 aurantia ; antice attenuatim producta, costis 7-8, medianis 

 magnis, laeviusculis ; squamis subapproximatis, arcuatis bre- 

 vibus, interstitiis leviter liratis ad marginem acute produc- 

 tis. — The singular obliquity and attenuation of the anterior 

 side, and the narrowness and comparative closeness of the 



s s 



