76 Shells as evidence of the Migrations. 
freshwater pearl mussels, Jethersa (Nile oyster), Unio, ete. 
at a very early period, using their valves as receptacles for 
paints, etc., in Pre-dynastic and later times. Whether 
they obtained pearls from these is not known, but the 
pearly nature of the shells themselves may have led to 
their being objects of appreciation. The detherne occur 
in the Nile as high as the cataracts of Robatas in Upper 
Nubia, and are described by Cailliaud, in his “ Voyage 
a Méroé,” as being a common article of food. ‘Their shells 
are collected by the natives in order to decorate the tombs 
of deceased relatives." Perforated discs of this shell were 
found in some numbers in a tomb of the Xviith dynasty 
(grave D 114) at Abydos," but whether they were used for 
ornamental purposes, such as necklaces or armlets, is 
difficult to decide. Judging from their size (diam. 27 mm.) 
they would not prove suitable objects for this purpose. 
There is no evidence to suggest that they were employed 
as a form of currency. 
Beyond the reference by Pliny” to pearl fisheries on 
the Mauritanian coast—probably inaugurated by the 
Pheenicians, who visited West Africa for gold—little is 
known of the use and exploitation of pearls in this part 
of Africa. 
On the east side of the African continent, pearl 
fisheries are known south of the Gulfof Aden. According 
to Kunz and Stevenson (of, cz, p. 153) “ little information 
exists as to the origin of these fisheries. In a paper 
published by the Lisbon Geographical Society, January, 
1903, Senor Ivens Ferranz states that, according to 
tradition, in remote times the Ibo Archipelago, on the 
'® Mary Roberts, “‘ Popular History of the Mollusca,” 1851, p. 311. 
1 T. Erie Peet and W. L. S. Loat, ‘f The Cemeteries of Abydos,” 
pt. iii, 1912-13. 35th Alem, of Egypt Explor. und, 1913, p. 30, pl. xii. 
46 Pliny, ‘‘ N.II.," bk. ix., ch. 56. 
