The valves of the three species were similar being an equivalve
held together by an elastic ligament leaving a scar on the hinge.
granosa are equivalve
, the sample was not separated into left or right valves and aggregated data are used in this analysis (e.
rhombeus fontainianus (Figure 1b and c) is subcircular, equivalve
Shell trigonal, equivalve
, inequilateral, gibbose, very tumid and posteriorly elongated to forming a slight wing.
In particular, the shells of the two larvae are equivalve
and edentulous, but it is not clear whether these features represent the ancestral condition or are adaptations to brooding (Chanley and Dinamani, 1980).
Shell large and flat, rounded to oval, equivalve
and inequilateral, similar to Anodonta, but with a solid, flat shaped and crenulated cardinal teeth on the right valve.