Fitzinger (1826) proposed the new generic name Chelodina for a turtle species previously identified as Testudo longicollis Shaw, 1793 (Goode, 1967), but did not provide an etymology. Agassiz (1844) derived the name from Greek chelys "tortoise" and Greek dine "circular rotation," and emended the spelling to Chelyodina. More recently, Webster's Third International Dictionary, The Century Dictionary and Cyclopedia, and Gotch (1986) have given the source as chelys and Greek deinos "terrible," while the Oxford English Dictionary suggested that the term "chelodine" is formed with vague reference to the Greek word chelone "tortoise." Such confusion is unnecessary, for zoologists and lexicographers appear to have overlooked a much more plausible etymology for Chelodina. Ancient Greek had special rules for making compound words more euphonious, often by contracting combinations of vowels. Modern zoologists rarely apply these complex changes in composing New Latin names from Greek roots. Early researchers trained in Greek and Latin, however, frequently shortened generic names in imitation of classical word-formation.