Pectens two[1254].
Abdomen divided into segments and terminating in a jointed tail, armed at the end with a sting[1255].
Spiracles four pairs.
3. Galeodea.
Def. Head distinct[1256].
Eyes two.
Mandibles chelate with dentated chelæ.
Palpi pediform, the anterior pair thickest with a retractile sucker.
Trunk consisting of two principal segments, with a minute supplementary posterior one[1257].