Some excellent reference material on the PERRO sessions:
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"The Mountain Song - 4" (8' 20"): As you'll see, this is the longest version and undoubtedly the most satisfying of the four. This is where Crosby's embryonic "Walkin' In The Mountains" suddenly reemerges and he goes through the verse and various chord sequences as an introduction to "The Mountain Song," to which it bridges seamlessly and beautifully. It's a remarkable segue which makes the listener keenly aware of how the song could have developed in a very different direction had Crosby stayed to contribute throughout its evolution. Speculation aside, what we do have is a return to the familiar pattern of banjo, guitars, bass, piano and percussion. Crosby reverts to his scatted counterpoint before it slips into a stunning instrumental section. Herein, the music weaves a genuinely hypnotic spell as it rolls effortlessly along the bed of Paul's banjo and Grace's piano, with Garcia picking exquisitely. After several minutes of this, the vocal pattern is re-introduced, now in a more restrained vein against instrumentation which has become subdued, with Grace and the Cros gently dancing around Jerry to the finale of a wonderful excursion.

"The Wall Song -1" (6' 00"): After a waggish intro from the composer, we're into a captivating version of a Crosby song which appeared in 1972 on the LP 'Graham Nash David Crosby.' On that take, the duo were backed by Garcia, Lesh and Kreutzmann and there's no reason to suppose that the same trio isn't in support here. The real distinction between the released version and this is the absence of Nash - though this is more than ably compensated for by the double-tracking of Crosby's wonderful voice, which provides an imaginative and memorable harmony. But there's a bonus. Just when listeners familiar with the 1972 record expect the track to finish, there's a lovely instrumental excursion with Garcia in winning form, shuffling percussion from Bill and a gentle ripple from Lesh. Really, this is so good it eclipses the official release by some distance - and should clearly have been included in the CS&N box of 1991.

**According to Steve Silberman, here's some add'l info on Wall Song***:

** The Wall Song on this tape is not the track used for Graham Nash/David Crosby, the excellent out-of-print album on Atlantic.
It is an out-take. Another, better performance was used for the record, although sadly, the record fades out just before the jam. That's especially
a shame because the band on both the PERRO tape version and the album version was: Garcia, Lesh, and Kreutzmann, plus Crosby and Nash. If a
choice were to be made for the CD, I would definitely go with the album version WITH the extended jam. It's a lot hotter than the PERRO tape take,
with a fiery Garcia & Nash driven peak with that ultra-sweet Garcia Strat sound of that era...

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