TELLINIDA. hi 
by a thickening of the margins; ligament external, apparently 
on the shorter side, inner edge of shell occasionally crenated. 
Lea described several somewhat different species under this 
genus. Conrad referred the orbicular forms to Mysia and Sphe- 
rella, and they certainly belong to the Lucinide, reserving the 
name Egeria for such forms as Hg. sublrigona (exii, 90) and 
ovalis of Lea. These shells externally very much resemble the 
subgenus Meera of Tellina, but as the latter never have the inner 
margin crenated, it is probable that the present classification of 
the group is the more correct one. Conrad,in his Check List of 
Eocene North American Fossils (1866), refers seven species to 
the group. Deshayes and others describe similar tertiary forms. 
oNcOPHORA, Rzehak, 1882. Founded upon O. socialis, Rzeh., 
a tertiary fossil, supposed to have inhabited brackish water. 
(Verh. K. K. Geol. Reichs., No. 3, 41, 1882.) 
IpHiGEentA, Schumacher, 1817. 
Syn.—Capsa, Lam., 1818. Donacina, Fer. 
Distr.—5 sp. West Indies, Brazil, West Africa, Pacific, Cen. 
America. I. Brasiliensis, Lam. (cxii, 88). Inhabits estuaries. 
I. ventricosa, Desh., has eroded beaks. 
Shell transverse, subequilateral, gibbous, covered with a thin 
Olivaceous epidermis ; hinge-teeth 2°2, one bifid, the other minute; 
laterals remote, obsolete in the left valve; margins smooth. 
FiscHeriA, Bernardi, 1859. 
Etym.—Dedicated to Dr. Paul Fischer, one of the able editors 
of the Journal de Conchyliologie. 
Distr.—2 sp. F. Delesserti, Bern. (cxii, 89). Africa. 
Shell transverse, equivalve, subequilateral, close, rather thick, 
with epidermis; right valve with a median, longitudinally chan- 
neled cardinal tooth, with additional rudimentary cardinals ; 
left valve with a median pit (to receive the cardinal of the other 
valve), and two slightly oblique, lateral cardinals; right valve 
with extremely thin, compressed lateral teeth, none in the left 
valve; muscular impressions distinct, pallial sinus large and 
deep; ligament short, rather elevated. 
: GALATEA, Bruguiere, 1792. 
Syn.—Egeria, Roissy, 1805. Potamophila, Sowerby, 1822. 
Megadesma, Bowdich, 1823. Galateola, Fleming, 1828. 
Distr.—\6 sp. Nile, and rivers of West Africa. G. radiata, 
Lam. (exii, 91). G. reclusa, Born (exii, 92). 
Shell very thick, trigonal, wedge-shaped ; epidermis smooth, 
olive ; umbones eroded ; hinge thick, teeth 1-2, laterals indistinct ; 
ligament external, prominent; pallial sinus distinct. 
Animal with the mantle open in front; siphons moderate, with 
6-8 lines of cilia, orifices fringed ; foot large, compressed ; palpi 
