Left Wrist Action
 

I think the 10-18-C and 10-18-D photos are switched in the 6th edition.

The photo labelled 10-18-C is labelled as "single" but I think it is actually showing "half", because the wrist isn't cocked.

The reverse is true for 10-18-D, I think should be labelled "single".

Is my observation correct or am I misinterpreting this section of the book?

Going in reverse
 

You are correct sir!

A Tale Of Two Photos
 

Drew is right, Ed. I've reprinted below a post I wrote last October responding to the same question.

The captions of the Single and Half Left Wrist Action Variations are wrong and should be reversed. This error has a long and persistent history:

The First Edition of TGM appeared in 1969 with an Errata page that contained fourteen errors. The eleventh of these was as follows:

"11. Page 111 Photos 10-18-C & -D are interchanged."

The error was corrected in the second edition (1971) and remained corrected in the third (1975). Inexplicably, it reappeared in the fourth edition (1979) when the photo layouts were changed and went uncorrected in the fifth and sixth editions (1980 and 1982). In his 96 handwritten pages of corrections, amplifications and additions slated for the as-yet-unpublished seventh edition, Homer notes that the typeface for the number and caption of paragraph 10-18-C is wrong and also that in the next to last line the word MOTION should be changed to MOVEMENT.

Nevertheless, the photo caption error persists. What to do?

Follow Homer's 1969 prescription and manually re-label the photos.