I'd heard a little about spindles traditionally used by the Coast Salish and, drop spindle user that I am, I was mystified why the whorls were described as bottom whorl, carved on the bottom, and why there was no notch or hook.
However, once I read that the Coast Salish used a tossed spindle and learned how a tossed spindle is used, descriptions of the spindle made sense. The carving, which would be out of sight on a drop spindle, is in view with a tossed spindle. A notch or hook, which is useful on a drop spindle, would hamper the roving on a tossed spindle since the roving is spun off the tip of the spindle.
The mechanics of a tossed spindle are described in Judith Buxton's Selected Canadian Spinning Wheels in Perspective: An Analytical Approach (Hull, QC: Canadian Museum of Civilization, 1992) p. 38, 48-52. There is greater distance on the shaft under the whorl, enough for the spinner to hold the end of the shaft in one hand and with the other hand, run the palm under the shaft to toss or spin it. The roving is not drafted by the fingers, but pre-drafted and run through a ring above the spinner to let gravity draft it.
A tossed spindle is suited to thick low-twist singles such as those used in Cowichan sweaters.
Please note that what I've written here is a synopsis of the book's description concerning tossed spindles in general and it's not meant at all to represent or explain Coast Salish spinning as a whole. That's not my bailiwick.
I'm wandering around here astonished, bumping into walls, and muttering, I never would have thought of that! Of course, I never would have come up with a drop spindle either.