sentences:  The length of the membrane that links the octopus's arms — the umbrella — was shorter in Robson's specimens than in Chun's, and there were additional warts with papillates on his specimens that were not described in Chun's specimen.Robson also noted a significant difference in the hectocotylus in Chun's specimen and those in his specimens.He noted that while two of his specimens appeared to be fully sexually developed, their hectocotyli looked comparatively underdeveloped.