paulzie,
Here's my O. erinacea var. ursina
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and O. erinacea
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Here is a link that might be useful: {{gwi:467960}}

Those are INCREDIBLE!!!! I Love the O. erinacea var. ursina... and the Pic of the O. polyacantha you posted was one I've drooled over many times!!!
On that site though, it's listed as O. polyacantha (erinacea)... Not sure if they think they are one in the same or not.. but according to Benson, they do look similar. Dave Ferguson wrote that too! I'm gonna have to send him an email about that! O. polycantha var. trichophora is described in Bensons book as looking like the one in the picture on that link! Has very long hair like spines like O. erinacea var. ursina but are flattened. O. polycantha rufispina looks similar to O. erinacea var erinacea and along their distribution lines, the distinctions are minimal.
O. erinacea also seems to usually have elongated pads where O. polyacantha has more round or oval pads... except in some varieties... So confusing!
Thanks Caudex.... Just keep adding to my confusion ;-)
Hey... shouldn't you be pruning some of your plants soon? :-D

Anything I can do to add to your confusion ;^)

Good memory, I will be pruning soon.

That O. erinacea var. ursina was purchased as a small pad about 15yrs from the Tilden Park Botanical garden plant sale. Have to get back up there, they have a wonderful desert area.

Wow! 15 years ago? Hasn't grown much has it?

Maybe I should freshen up the soil, it's been in that pot for at least 7yrs. Probably would be larger if I watered it more often or fed it once in a while.

The second pic is Ferocactus acanthodes(cylindraceus) and the last pic looks to be a small Echinocactus polycephalus with long central spines.