950 OYSTERS, AND ALL ABOUT THEM. 



of Rebata, and below the peninsula of Meroe. The inha- 

 bitants collect them on the banks of the river, to ornament 

 their tombs with them, and they say that they come from 

 the more elevated parts of the Nile, from Sai'da, where 

 they are eaten." M. Cailliaud found them as far as Fazogl, 

 the most distant country into which he penetrated from the 

 Blue River. 



In Sennaar the inhabitants informed M. Cailliaud that 

 during the summer season, when the river was low, they 

 took them with the animal ; but notwithstanding all his 

 endeavours, M. Cailliaud could not obtain any living 

 specimens, they river being then always too high. They 

 are said to be common in the Jaboussi, a river which runs 

 into the Blue River, and in all appearance the numerous 

 confluent streams of this great arm of the Nile produce 

 them also. The number found upon the tombs throughout 

 Ethiopa is so great, that it is astonishing that Bruce and 

 Burckhardt should not have mentioned them. (See " Zool. 

 Journ.," vol. i.) 



M. Deshayes, in his treatise on the genus, in the 

 " Encyclopedic Methodique," states that individuals of the 

 same species adhere by the one or the other valve indif- 

 ferently, which is not the case either in the oyster or the 

 Chamae. The Chamae, however, as has been observed by 

 Mr. Broderip, are found to be attached sometimes by the 

 right and sometimes by the left valve. 



The shell of Etheria is characterised as thick, nacreous, 

 adherent, very irregular, unequivalve, and inequilateral. 

 The umbones are short, thick, and indistinct ; the hinge 

 is toothless, irregular, undulated, and callous ; the liga- 

 ment is longitudinal, tortuous, external, and penetrates 

 pointedly into the interior of the shell. The muscular 



