102 



NATURAL HISTORY. 



the inner surface is a rich red and green, which makes it valuable for 

 papier-mach^ and lacquer inlaying. The trade in it is considerable, San 

 Francisco alone exporting, in 1867, 7426 bushels, which were valued at 

 thirty-six thousand dollars. 



The wentle-traps (Scalaria) are noticeable only from the high prices 

 which one of the species has brought in times past. To-day it is worth 

 l.iii i dollar or two, but a hundred and a hundred and fifty years ago it 

 sold for one hundred or even two hundred dollars. It is not a handsome 

 Bpecies, and nothing about it would indicate that it had any particular 

 value. < >ne of the volutes (Voluta), on the other hand, has brought high 

 prices ; but this species has a beauty of its own. Voluta junonia has sold 

 for two hundred dollars, and even to-day will bring seven or ten dollars. 

 Others of the genus are worth even more to-day. 



The olive-shells (Oliva) have always been favorites with collectors, 

 although they have never brought prices to compare with those quoted 



in the last paragraph. 

 They have had to de- 

 pend for favor upon 

 their own beauty, and 

 their polished and porce- 

 lain-like surface makes 

 them very attractive. 

 The mitres (Mitra) are 

 long and slender, but 

 bear but a slight re- 

 semblance to the mitre 

 of a bishop. Both mi- 

 tres a ml olives live in tropical seas, the former being nocturnal in their 

 habits. During the day they hide under some rock or bit of coral, but 

 .n'tcr (lark they sally forth to feed on other molluscs. 



Tin iv arc several molluscs which secrete substances suitable for use as 

 dyes, but probably those from which the ancients obtained the celebrated 

 Tynan purple are entitled to the first place. There is considerable uncer- 

 tainty as to the exact processes which were followed, but of some of the 

 steps there is not the slightest doubt. In the rocky shores of the eastern 

 Mediterranean there remain to this day the traces of the old dye-works of 

 two and three thousand years ago. In the rocks still remain the excava- 

 tions which served as mortars for bruising and crushing the molluscs, and 

 in st inie of the mortars, fragments of shells still remain, so that we know 

 beyond a doubt the species employed in coloring, although we may not be 

 able to tell exactly the proportions of each used, an element which seems 



Fig. <X>.— Black olive-shell {Oliva maurus). 



