rachianectes

from The Century Dictionary.

• noun A genus of whalebone whales of the family Balænopteridæ: and subfamily Agaphelinæ, containing the gray whale of the North Pacific, R. glaucus, combining the small head, slender form, and narrow flippers of a finner-whale with the lack of a dorsal fin and absence of folds of skin on the throat of a right whale.