Following the first systematic part, in this paper the author describes the biological observations made on these Isopod Crustaceans of underground waters. The different sexual characters of the particular groups and the related differences in the behaviour before copulation are described. During the embryonic and larval development small differences between sub-genus are reported. To the differences in Caecospaeroma (according to Daum) the first and second “mancastadium” and another “postmanca stadium” with pereiopods VII not wholly formed have to be added. The author describes the growth of the different parts of the corps and the extremities, comprising the sexual characters.