The mark in the top photo looks like the Diana's head used in Austria 1886 - 1922. See http://www.925-1000.com/foreign_marks.html" onclick="window.open(this.href);return false;
Well, after playing with the image for a while, think I have it worked out as the French crab mark for provincially made .800 silver. The cartouche form is also a (pentafoil?), just like the Austrian Diana.
The maker's mark on this pin is also in a French format, which brings us to pre-war French Morocco, Algeria or thereabouts.
Tom is very probably right - and certainly the maker's mark in a lozenge is typically French-looking.
This French children's book is about a crab named Poinçon, of course!