yep, some type of terrier. I am not entirely familiar with all the terrier breeds, and I don't feel like spending an hour on wiki (I know these things happen, it always starts with a simple curiosity)... so I don't want to hazard a guess between a full blooded breed or random terrier mix.
Terrier-dominant mutts tend to be good dogs, as long as they are raised by decent owners. Amazing family pets, usually great around anybody you allow on your property.
We had a larger terrier mutt (45 lbs or so, and slender), not entirely sure of what all was in her. She had characteristics of quite a few breeds, definitely was a true multi-breed mutt. We, and the vets, think the dominant breeds had been a terrier of some sort, and a standard poodle. Standard poodles are adorable lab-sized walked carpets, and she had some resemblance in the body and face, though her coat was almost entirely like most terriers.