CONCHIFERA. 743 
fig. 3. The Venus islandica of Broconi (and Cyprina gigas LaM.) a fossil 
species from the calcaire grossier and other tertiary strata, does not belong 
to this genus, but to the preceding, Venus Brocchii DESH., BRonn Leth, 
Tab. 38, fig. 1. 
Family XIV. Cycladea. Mantle concrete posteriorly, fur- 
nished with two trachee. Ligament internal. Foot large, not 
byssiferous. Shell equivalve, free, gibbous or ventricose. Hinge 
with teeth under the point various, sometimes obsolete, and 
with lateral teeth gone. ‘Two muscular impressions remote. 
This small family contains conchifers that live in rivers and 
in fresh-water lakes, like the NVaidea, from which it sufficiently 
differs, although Jridina (see above, p. 736), on account of the 
united mantle and the two trachee might be brought to it. The 
present family is nearly allied to the preceding, whose place they 
represent in fresh water. 
Glauconome GRAY. Cardinal teeth three, with middle one larger, 
often bifid. Shell elongate, transverse, with points eroded. 
Fresh-water bivalves, which in external appearance almost resemble 
Anodonta or Unio. They are all exotic. It seems that some fossil fresh- 
water shells, which previously had been referred to the genus Venus, find 
their true place here. 
Galathea Bruc., LAM., Potamophila Sow. Shell trigonal, sub- 
equilateral. Teeth under the pomt two in right valve, with a 
small triangular median pit receiving the third intermediate tooth 
of left valve. Ligament prominent, turgid. Animal with two 
trachez, not concrete, and foot oblong, compressed. 
Sp. Galathea radiata Lam. (Venus subviridis and Venus hermaphrodita GMEL.), 
Lister Conchyl. Tab. 158, fig. 13, Hncycl. méth., Vers. Pl. 250, fig. 1, 
Lamarck Ann. du Mus. v. p. 430, Pl. 28, SANDER Rane Notice sur la 
Galathée, Ann. des Sc. nat. Tom. XXv. 1832, pp. 152—164, Pl. v. In the 
rivers of W. Africa; the description of RANG first made the animal known, 
the shell alone of this species having been previously known, which some 
writers stated to be from Ceylon. 
Cyrena Lam. Shell thick, ventricose, corticate, with points 
eroded or decorticate. Hinge with three teeth in each valve, 
(Animal with two trachez separate from the base throughout.) 
Sp. Cyrena Zeylonica LaM., Buatnv. Malacol. Pl. 73, fig. 2; a larger variety 
of this species occurs at Java, see A. Mousson, Die Land- und Stisswasser- 
Mollusken von Java. Zurich, 1849, 8vo, Taf. x1, All the species of this 
genus are exotic. 
