The new and remarkable forms of #Botryodea#, which I subsequently found in the Challenger collection, demonstrated that the #Botryodea# differ from the other #Cyrtellaria# (the #Cyrtoidea# as well as the #Spyroidea#) in a far higher degree than I formerly had supposed. A synopsis of the figures in Pl. 96 will give sufficient evidence of this view. Therefore in my Prodromus (1881, p. 439) {1104}I completely separated the #Botryodea# (or Botrida) from the other suborders of #Cyrtellaria# (Spyrida and Cyrtida). Bütschli gave, in 1882, in his paper on the Cyrtida (_loc. cit._) a very accurate description of _Lithobotrys geminata_, and pointed out its close affinity to _Lithocorythium_ and _Lithomelissa_, and the importance of an oblique septum separating the cephalis into a smaller anterior and a larger posterior lobe. His views on the #Botryodea# (as a subordinate group of the #Cyrtoidea#) are however incomplete, since the peculiar forms, described in the following pages, were unknown to him. According to the wide morphological divergence of the different #Botryodea#, and the numerous peculiar forms developed from it, we here divide the whole group into three families and ten genera, with fifty-five species. These form, however, only a small part of the large and varied mass of closely related forms which are found in the rich collections of the Challenger. The great difficulty of researches on their intimate structure, and the great amount of time required for it, prevented me from giving a more complete and exact description than the one here given. The observation of the small shells from all the different sides is a difficult task, requiring years of work, and its satisfactory explanation would be possible only by means of numerous figures. The three families of #Botryodea#, here described, correspond to the three first groups of #Cyrtoidea#. The first family, Cannobotryida, corresponds to the Monocyrtida clausa and to the Zygospyrida; their shell consists of a cephalis only, without subsequent joints. The second family, Lithobotryida, corresponds to the Dicyrtida and Phormospyrida; their shell is composed of a cephalis and a thorax, both joints being separated by a transverse cortinar septum and a collar stricture. The third family, Pylobotryida, has a three-jointed shell, like the Tricyrtida, with cephalis, thorax and abdomen.