Properly chronicling the history of a long-lived label is a tricky prospect and usually requires a substantial boxed set. But fiercely independent Chicago-based Alligator Records, the home of "Genuine Houserockin' Music," has limited itself to a two-disc, 38-track snack-sized sampler that touches on great moments and key acts, including Koko Taylor, Mavis Staples, Eddy "the Chief" Clearwater, Tommy Castro and the Holmes Brothers. It also features such discoveries as Shemekia Copeland, Janiva Magness and JJ Grey & Mofro. The set highlights collaborations between Lonnie Mack and Stevie Ray Vaughan, Roy Buchanan and Delbert McClinton, and the trio of Albert Collins, Robert Cray and Johnny Copeland. Elsewhere, selections from new releases by Roomful of Blues and Marcia Ball show that Alligator still has plenty of bite in 2011-and the past decade is the most widely represented. While it would have been nice to hear some early, out-of-print material from Hound Dog Taylor and others, this is a serviceable representation of Alligator's history that's sure to send listeners deeper into the individual artists' catalogs.