This is another one of those items that is either missing or deteriorated on many Type 34s. The VW Parts List calls it a "boot - air cleaner" (311 129 695 B). It's an accordion rubber boot that connects the end of the air cleaner to the warm air mixing box (see picture above). The early boots had four bellows, and later ones had only two.
Early Type 34s had screw-type hose clamps to secure these boots. At some point in production a quick-release clamp design replaced the early screw clamps. The quick-release clamps are much easier to work with.
Note from Everett Barnes: Quick-release clamps were not used until the 1966-67 time frame (I do not know the exact date or VIN), and only on the air cleaner side. Of course, they are nice to have as it makes it much easier to remove the air cleaner.