The Collaborative International Dictionary of English v.0.48:

Herpetology \Her`pe*tol"o*gy\, n. [Written also, but less
   properly, erpetology.] [Gr. ? a creeping thing, reptile (fr.
   ? to creep) + -logy: cf. F. herp['e]tologie.]
   The natural history of reptiles; that branch of Zoology which
   relates to reptiles, including their structure,
   classification, and habits.
   [1913 Webster]

WordNet (r) 3.0 (2006):

herpetology
    n 1: the branch of zoology concerned with reptiles and
         amphibians