* * *

Diagram showing
the relationship between age (from thin sections including estimations of the eroded umbonal part) and shell length in *U. crassus* from river Sauer (Luxembourg and Belgium populations) and river Our (Luxembourg population).

- [![Age UC - Age determination of Unio crassus](/thumbnails/55298-212-0-Max.jpg)](/files/55298.jpg "Age UC - Age determination of Unio crassus")