I remember stoping buying these cos there were bones in, oh and they stunk to high heaven
Read Messybeast,Robbo... it will open your eyes.
If you're really curious about how cat food is made, Messybeast does a very clear description. But I'd take it as read that all animal foods meat is mushed and boiled to hell before it gets reformed into those tiny neat little cubes. Any harmful bones won't survive the rendering process. So relax on that worry...
They're fine. The small bones in fish like salmon are soft and don't cause the problems that larger bones do if they splinter.