“SONG X.” Pat Metheny/Ornette Coleman. Geffen GHS 24096. For his first album on Geffen, Metheny has joined forces with the man he calls “the greatest improviser of the last 30 years.” Essentially, he has moved more in Coleman’s direction than Coleman has adjusted to Metheny, a fact that is underscored by the presence of two regular Coleman sidemen, his son Denardo (who shares the percussion responsibilities with Jack de Johnette) and the bassist Charlie Haden, who provides the group with a firm foundation of which it is often in obvious need.

The longest and most adventurous cut, “Endangered Species,” involves blistering, at times near-chaotic improvisational interplay, with Metheny using a guitar synthesizer. This is one of the four pieces for which he shares composer credit with Coleman, though “Trigonometry” and “Song X Duo,” also given dual credits, are strongly reminiscent of the lines Coleman was inventing in the early 1960s. Haden’s walking lines under Coleman on “Video Games” and the melodic theme of Coleman and Metheny’s “Kathelin Gray” provide some of the best integrated work. Coleman switches to violin, on which he meanders to minimal effect, on “Mob Job.”

A problem with the collaboration is that at times the two leaders don’t quite get it together; it sounds as though Metheny, instead of playing direct unison, listened to Coleman, then echoed his notes a millisecond later. Still, this marks an intriguing and intermittently successful change of pace for both men. 3 1/2 stars.