In the aglaopheniid genus Cladocarpus Allman, 1874, there are two different types of phylactocarps. In the first type the rachis (axis) of the phylactocarp is homologous with the axis (hydrocaulus) of the Aglaopheniidae, being either unbranched or dichotomously branched with the axis composed of segments each bearing an apophysis supporting a nernatophorous branch. The apophyses, and consequently also the branches, alternately point left or right. The type of the genus, Cladocarpus formosus Allman, 1874, has this morphology. In the second type the rachis is structurally similar to that of the hydrocladia; the composing segments bear pairs (or a pair) of nematothecae, arranged in opposite pairs. Species with this type of phylactocarp have so far been placed in Cladocarpus or in one of the later described genera Dinotheca Stechow, 1911, or Cladocarpella Bale, 1915. These genera have been synonymized with Cladocurpus by some authors. The place of Aglaophenopsis Fewkes, 1881, and Nematocarpus Broch 1918, is not clear; the genera evidently are closely related and have occasionally been synonymized or brought to Cladocarpus. The structure of aberrant phylactocarps in an undescribed species of Cladocarpus has affinities with the gonosome of Aglaophenopsis; but it is too early to make a decision now on the taxonomic importance of this aberrant gonosome. The structure of the gonosome of Streptocaulus pulcherrimus Allman, 1883, described by Quelch (18851, approaches that of the second type in Cladocarpus closely, though the spirally arrangement of the hydrocladia is only observed in Streptocaulus. The peculiarity develops from an initially pinnate arrangement of the hydrocladia. It appears that Streptocaulus is the oldest available genus name to accommodate the species with the second type of gonosome so far placed in Cladocarpus.