CONCHIFERA. 737 
ment external, penetrating partly internally into a groove. Hinge 
callous, edentulous. 
LAMARCK, who first made this genus known, thought that it was found 
in the sea. It was placed in the neighbourhood of the Oysters, from which, 
however, the shell differs by the two muscular impressions. Since that 
time these conchifers were found in the Nile by the traveller Camuaup. 
The animal was afterwards described and figured by RANG and Quoy. It 
agrees, as RANG remarks, with that of Unio and Anodonta, so that in fact 
the Htherie might be shortly characterised as irregular Anodonta with one 
of the two shells attached, 
Comp. Lamarck Ann. du Muséum, x. pp. 398—408, Pl. 29—32; Fé- 
RUSSAC Notice s, 1. Ethéries trowvées dans le Nil, Mém. de la Soc. d’ Hist. 
nat, de Paris, 1. 1823, pp. 353—372; Rane et Cartuaup Mém. sur le genre 
Ethérie et descr. de son Animal, Nouv, Ann, du Muséum, ut, 1834, pp. 128 
—144, Quoy in Lesson Illustr. de Zoologie, Pl. 58, 59 (1835). 
Sp. Ltheria Lamarckit Féruss., Eth. elliptica Lam. (and Eth. trigonula 
ejusd.), Ann. du Mus. X. Pl. 29, 30, fig. 1, Buatny. Malac. Pl. 70 bis, fig. 
2, &c., GuERIN Iconogr., Mollusq. Pl. 26, fig. 8 
All the known species live in fresh water in Africa, and would seem, 
with Jridina, to represent the Uniones so numerous in America, which 
are not abundant in Africa. 
Family IX. Carditacea. Mantle cloven. Foot compressed, 
suleate, not byssiferous. ‘Tentacles around the mouth divided into 
several lobes. Shell regular, free, inequilateral, equivalve. ‘T'wo 
muscular impressions remote. ‘Teeth of hinge mostly two, in some 
a single tooth, the anterior being obsolete. 
Cardita Bruce. (exclusive of species), Desuayves (Cardita and 
Venericardia Uam.). Shell suborbicular, transverse or oblique, 
often costate longitudinally. 
An historical review of the genus Cardita, and of the modifications it 
has undergone, was given by DesHayEs Encycl. méth., Vers. 11. 1830, pp. 
194—196. All the species now living are marine, mostly small or only of 
moderate size. The fossil species are numerous, especially in the caleaire 
grossier, as Cardita imbricata, Venericardia imbricata Lam., Lister Hist. 
Conchylior. Tab. 497, Buatnv. Malacol. Pl. 68, fig. 3, DesHarEs Conchy- 
liol. Pl. 31, fig. 6, &e. 
Family X. Chamacea. Mantle excised with a middle aperture 
for the foot, and furnished with two distinct foramina in the tentacu- 
late margin (trachea of mantle and trachea of gills), elsewhere 
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