From the Catskill fly tyers guild website:

Catskill Style involves tradition and discipline regarding proportion and choice of materials. This doctrine has been concisely defined for us by Harry Darbee in his book "Catskill Flytier":

"Its characteristics: a good sized hook, typically size 12 Model Perfect, a notably lean spare body, usually spun fur or stripped quill of peacock herl; a divided wing of lemon colored mottled barbules of a woodduck flank feather; a few sparse turns of incredibly stiff, clean, glassy cock's hackle, mostly either blue dun or ginger.

The wings and hackle are set back from the eye of the hook, leaving an unusually long clean "neck" at the expense of a slightly shortened body."

If you're interested in studying "Catskill Style" further I would definitely suggest reading 'Tying Catskill-Style Dry Flies' by Mike Valla. Not only a good source of information regarding some of the patterns found but a very good history of the Catskill region, it's fishermen and tyers. I live in upstate NY about 4 hours from the Cats and NEVER realized the rich history found there.