V L A C IJ N A, 



Species i . ( Fig. 

 Placuna 



lid Plate V. tig. h, Mus. Brit.) 



l.oiiATA. I'lti. tfStA siiliqimdratd, compressd, 

 rix versus umbones cmivexd, aUiidd rel fiisco-pur- 

 ptireo radiatd, costis pavlo elevatif, latis rotundis \ 

 radiatdjintiis purpttreo-fusro, vel maadato-nebuhitd ,• 

 marginibus lateralibus et ventralilius lobatis ; drnti- 

 ()us mhwqualibus, modernte divergentihus. 

 The lobeh Placuna. Shell siibquadrate, coin])rcssed, 

 slightly convex towards the umboes, whitish or 

 lirownish purple-rayed, rayed with slightly elevated 



Novoiul)' 



broad rounded ri 

 cloudy-spotted : l,i 

 teeth nearly eiiual. 



ately 



Sowi 

 llab. 



i;nv. 



Port Kssingtuii. 

 Tlir iH'culiarity of this shell consists in its licin.i; 

 rayed with slightly raised ribs, accompanied with 

 great flexuo.sity in the lines of growth and lobes on the 

 lateral and ventral margins of the valves. The teeth 

 are similar to those oi Placuna jiapi/racm. 



