Found dead in river. I'm posting this as F. flava but I don't feel very confident about it. It does have a slight sulcus but it seems to be very inflated with a large and bulbous umbo. The beak cavity is very deep and the interdentum trails across the ventral side of the pseudocardinal tooth. The lateral teeth are very short.
Devil's River Bioblitz 2024
If there are different species then I will separate, please let me know.
Found this in a muskrat midden. Interesting scar / damage!