Saddle-shaped

from WordNet (r) 3.0 (2006)

saddle-shaped
    adj 1: shaped in the form of a horse's saddle

from The Collaborative International Dictionary of English v.0.48

Saddle-shaped \Sad"dle-shaped`\, a.
   Shaped like a saddle. Specifically:
   (a) (Bot.) Bent down at the sides so as to give the upper
       part a rounded form. --Henslow.
       [1913 Webster]
   (b) (Geol.) Bent on each side of a mountain or ridge, without
       being broken at top; -- said of strata.
       [1913 Webster]