PQa PHILOSOPHICAL TEANSACTIONS. [aNNO ] 692-3. 



like to that of the purple fish. He means what was used in his time ; when it 

 6eems the unguis odoratus was lost, or was not brought to Europe. But it will 

 appear from the same Dioscorides, that the unguis was no operculum ; and it 

 will be worth the while to show this mistake, and consequently the errors of the 

 moderns in substituting the operculum of a marine turben for the true unguis 

 odoratus. The unguis odoratus, according to Dioscorides is found in the lakes 

 of India, where nard grows ; on which account the conchylia feeding on nard 

 are aromatic. It is gathered after the lakes are dried up with the summer heats. 

 And he concludes, that the conchylium itself, burned or calcined, is of the 

 same efficacy with the purpura and buccinum burned. In the chapter on nard, 

 he further says, that the Indian nard grew near the river Ganges, that is, in 

 certain lakes, caused by the overflowing of that river. Hence it appears, 



1. That the unguis odoratus was part of a fresh water conchylium. 2. If it was 

 generated in the nardiferous lakes on the river Ganges, how comes it that the 

 same was brought from the Red Sea and Babylon ? And why should the shell 

 itself be brought so far as from the river Ganges to Greece, since the operculum 

 was rarely a tenth part of the shell itself? Now if it was not used to be brought 

 and exposed to sale, to what purpose to declare its virtues, or how could the 

 experiment be made ? I conjecture therefore, that the true unguis odoratus was 

 something like the half of a pectunculus fluviatilis, so common in the river 

 Thames, of the size and thickness of my thumb nail, and that for these 

 reasons. 1 . That the unguis odoratus'seems to have been a fresh-water bivalve 

 or muscle, because it was not gathered till the lakes on the river Ganges were 

 dried up. Now bivalves are always buried in the sand and mud, and never rise 

 up and swim about or float as the turbinate snails do, to which latter only the 

 operculum belongs, and which therefore were at all times easily to be caught. 



2. He calls this snail conchylium, and by that general name distinguishes it 

 from'all the other sorts, concerning which he treats in several chapters ; which 

 though in general it take in both kinds, as well turbinate as bivalve, yet it more 

 particularly denotes a concha or bivalve. 3. The onyx is expressly reckoned by 

 Pliny among the bivalves. For (1. 32, c. 1 1,) he makes all these synonimous, 

 soleu, aulos, donax, onyxi, dactylus. And again more particularly, (lib. g, 

 c. 6l,) he says that the dactyle are of the bivalve kind, and so denominated 

 from their resemblance to the finger nails. So that in all probability the onyx 

 odoratus anciently brought out of the fresh-water lakes about the Ganges in 

 India, was not unlike the common onyx of the Mediterranean, which was of 

 the solen kind. Whatever the blatta byzantina of our shops is, it has certainly 

 nothing of the characters of the ancient aromatic unguis ; which in all probabi- 

 lity was lost on account of the difficult passage fronj th« Ganges into Europe. I 



