Great job Marlo. The F.angusta have always troubled me. Here is what I've come up with on them. Could be way off on my thoughts.
In the picture are Fissurella rosea,barbadensis,angusta that I have collected. I went to Abbott/Morris 1995(4th edition) for the description of F.angusta. They say- about 3/4 in long,rather flattish,somewhat pointed in front,brown around orifice. The what I have as angusta in the picture is nothing like the other two,so my question would be- if it's not a F.angusta then what did I find?