For whatever reason, bluegrass purists have been reluctant to embrace the next generation of string bands crowding America's festival circuit. The latter's new style of fast-paced mandolin meandering leaves die-hard enthusiasts wondering exactly what they're hearing. What should they call it? Punkgrass? Bluerock? Minnesota's Trampled by Turtles calls itself an "original, non-traditional bluegrass band." As far as handles go, that one's a little long-winded and boring — but whatever tag is stuck on their jug-thumpin' sound, the Turtles could sit on the string-rock board of directors alongside such homegrown acts as the String Cheese Incident and Yonder Mountain String Band. Live, the band prefers to sit down while performing, which is a bit tame for the foot-stomping licks its members proffer. Even so, the group manages to emanate a great deal of energy on stage. Songs like "Ceiling Slide," off the outfit's latest effort, Trouble, are sure to have the Bluebird crowd hootin' and hollerin' in the fresh blades of...nü-grass?