The Semantiscida, which do not possess these three basal cortinar feet, are the simpler forms of the family. The simplest of all, and perhaps the common ancestral form of the whole family, is _Semantis_ (Pl. 92, figs. 1, 2). It may be derived from _Archicircus_ or _Zygocircus_ by development of two pairs of horizontal apophyses on its base, around the porochora of the central capsule. The two rods of each side (right and left), becoming curved one towards the other, and meeting laterally, form a simple horizontal gate, and the two paired basal gates together, a horizontal ring or basal ring, to which the primary sagittal ring is perpendicular. In the next allied genus, _Semantrum_ (Pl. 92, figs. 3-5), three pairs of horizontal apophyses are developed, and therefore two pairs of basal gates produced, an anterior and a posterior. In the third genus, _Semantidium_ (Pl. 92, figs. 6, 7), three pairs of basal pores or gates are visible, surrounded and separated by four pairs of horizontal apophyses, which arise from the base of the sagittal ring. Finally, in _Clathrocircus_ (Pl. 92, figs. 8-10) the number of apophyses is much increased, and two parallel rows of pores are developed along the two sides of the sagittal ring. The basal plate or the "seal," developed from the base of the primary sagittal ring or "signet-ring," is therefore a horizontal ring, which becomes bisected by the latter, and exhibits either one pair of primary "basal gates" or two or three pairs of these important basal pores, rarely more. Since these pores possess the greatest morphological value, and are probably everywhere homologous, we give to them and to the separating apophyses certain names, and call the anterior pair of gates, "jugular pores" (_i_ in our figures, the pair I of Bütschli); the middle (usually the largest) pair, "cardinal pores" (_k_ in our figures, the pair II of Bütschli), and the posterior, smaller pair, "cervical pores," _l_. The typical pairs of rods, by the union of which these basal pores arise, are the following:--(1) the clavicular or furcular rods, _f_, the first pair (rods _e_1 of Bütschli), (2) the coracal rods, _e_, between the jugular and cardinal pores (rods _e_ of Bütschli), (3) the scapular rods, _g_, between the cardinal and cervical pores (rods _e_2 of Bütschli), (4) the cervical rods, the fourth pair of apophyses, the most posterior, _h_. Bütschli supposes that the topographical succession of the three typical pairs of basal pores is also the chronological succession, the jugular being formed first, the {955}cardinal second and the cervical pores third but it seems that this succession is often altered and that the cardinal pores (the largest), appear first, the jugular pores (in front of them) second and the cervical pores third (or perhaps sometimes in the inverse succession).