Published online by Cambridge University Press: 06 April 2009
Generic Diagnosis, ♀. Cephalothorax with transverse lateral expansions, small in young, resembling a hammer in old specimens, between whose anterior surfaces projects the head. Neck smooth, cylindrical and without swimming feet. Trunk much enlarged transversely, smooth, flattened dorsiventrally, bearing a pair of posterior appendages profusely and dichotomously branched. Abdominal appendages reduced to two small knobs; or one undivided abdomen.Egg-strings long and straight; eggs multiseriate. Two pairs of antennae, twopairs of maxillae, one pair of maxillipedes.