74 



The " Many-ridged Harp ", the " Eose Harp " the " David's Harp " and 

 others, are shells of such familiar occurrence, that it will be interesting to 

 form some acquaintance with the animal from wliich they derive their 

 existence. It will be seen on reference to plate E that the soft parts of 

 Harjpa are of unusually large size, the disk being elongated posteriorly to a 

 point, and widely auriculated in front ; indeed, it is described as being so 

 large and muscular as to be scarcely susceptible of being contracted within 

 tlie aperture of the shell. The animal of the ' Harps ' , like that of the 

 ' Tuns ' , appears to exhibit a rather more than ordinary degree of activity ; 

 it is related both by M. Reynaud and M. Quoy, to have the faculty of 

 spontaneously divesting itself of a portion of the disk, under irritation or 

 emergency, after the manner of the Atmelides, which it is well known often 

 separate in pieces from violent contraction. The colours of the animal are 

 scarcely less vivid than those of tlie shell, being of yellowish-green and rose, 

 curiously ocellated tlu-oughout, wliilst the respiratory siphon is striped 

 across. 



The shells of tliis beautiful and very limited genus are too well known to 

 require mention ; it may be added, however, that the prominent longitudinal 

 ribs, which impart the harp-Hke symmetry of structiu-e to the shell are 

 regarded as so many varices ; analogous in structure to the varices in the 

 shell of Murex, each forms in its turn the margin of the aperture, and, the 

 intervals between them are probably of rapid growth. 



The Harpa mostly inhabit the shores of Ceylon, the Mauritius, and the 

 Philippine Islands ; one species, the H. crenata, is from Mexico. They 

 are all extremely rich in colour, and are not less remarkable for the bright 

 enamelKng of the body-whorl, in the immediate vicinity of the aperture. 



Species. 



1. articularis, Lam. 4. gracilis, Brod. 7. nob ills, Rumph. 



2. couoidalis, Lam. 5. imperialis, Chemn. 8. rosea, Lam. 



3. crenata, Swain. (J. minor, Rumph, 9. ventricosa, Lam. 



Figures. 



Harpa ventricosa. Plate E. Shell with animal, showing its large elon- 

 gated disc, auricular appendage in front, tentacles, eyes, and erect 

 branchial siphon. — From the ' Voi/age de I' Adrolahe' . 



HaFvPa imperialis. Plate 5. Pig. 2G. Shell, showing its many-ridged 

 structure, arising from the rapid succession of varices. 



