UNIVALVES. 



PLATE VIII. 



Genus. HEXAPLEX. 

 Character. Shell univalve, spiral, divided longitudinally by six folds, from whence 

 its name is derived ; these folds are membranaceous and tuberculous, and some- 

 times spreading out into branched horns ; the mouth round ; the beak long, and 

 armed with several calcaria or spurs, in a similar manner to the genus Triplex. 



Species. 



No. 1. Hexaplex tenuis. Shell brown; the spines some long and branched, 

 some short and round ; the mouth gray, with a white border. This curious 

 shell is a native of the South Seas, and is from a specimen in the Collection 

 of Mrs. Bligh. 



No. 2. Hexaplex anatomica. Shell white, slightly tinged with a blue or purple 

 effect : the spines very irregular in their form, some of them resembling a 

 death's head, others very short. A native of the East Indies. From a spe- 

 cimen in the Collection of Lord Valentia. 



No. 3. Hexaplex fusca. Shell brown, with flattened and divided spines; edge 

 of the mouth white, inside brown. This curious shell has a distant resem- 

 blance to a cart-wheel or to a wind-mill. It is drawn from an excellent 

 specimen in the Collection of Mr. Jennings of Chelsea. 



No. 4. Hexaplex foliacea. Shell white, having six brown folds or septse, richly 

 diversified, and adorned with leafy branching integuments. It is difficult, 

 nay almost impossible, to do complete justice to the beauty of this graceful 

 and interesting shell ; it has so charming a variety of form, and is so richly 

 and curiously ornamented. It is drawn from a valuable specimen in the 

 Museum of Dr. Lettsom at Camberwell. 



No. 5. Hexaplex punctuata. Shell of a yellow brown, spotted with dark brown ; 

 edge of the mouth white, and slightly denticulated. Native place unknown. 



No. 6. Hexaplex ovata. Shell brown, with a white mouth, the form singular, 

 and nearly oval ; spines very short and irregular ; the beak quite straight. 

 A native of the South Seas, and very rare. From the Museum of Mr. 

 Spurrit, Lambeth. 



REMARKS. 



The shells which constitute the genus Hexaplex have a striking analogy to those of the 

 Triplex genus already described, and to the Plates of which we refer our reader ; the dif- 

 ference consists almost wholly in the number of septse, or divisional folds, of which the 

 Triplex has only three, and winch of course makes a difference in the beak and the calcaria, 

 or spurs, attached thereto; it differs materially from the Polyplex genus, in the same respect 

 of folds, the Polyplex having, as its name denotes, a great number of folds placed on its 

 body and spire. The shells of this family are chiefly found in the South Seas, and exhibit 

 much elegance and singularity of form ; many fossil shells, however, of the genera Triplex, 

 Hexaplex, and Polyplex, have been found both in France and England, though differing 

 in their exact specific form from any at present living ; a circumstance which would seem 

 to confirm the general opinion that the Deluge was universal; since we discover shells de- 

 posited in the earth in various parts of Europe, of which living specimens are now only to 

 be found in the most distant seas. 



