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 e1 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 e2 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 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).
The Cortiniscida, the second subfamily of Semantida, differ from the preceding Semantiscida in the possession of three typical basal feet, which are probably inherited from the Cortinida, and perhaps indirectly from the Plagonida (Plagoniscus). The simplest and the most important form of this second family is Cortiniscus (Pl. [92], figs. 11-13), differing from its probable ancestral form, Cortina, in the development of a basal ring, produced by horizontal union of the basal apophyses. The three typical feet are the same as in all triradiate Nassellaria, two paired pectoral feet (p1, p11) diverging on the anterior base of the sagittal ring, whilst the odd caudal foot (c) lies on its posterior base in the sagittal plane and appears as a basal prolongation of the dorsal rod of the sagittal ring; the upper part of the dorsal rod is usually prolonged into an ascending apical horn. In Stephaniscus (Pl. [92], figs. 14, 15) four basal feet are visible, an anterior or sternal foot (z) being added as a prolongation of the basal rod of the ring, opposite to the caudal foot. Finally, Semantiscus (Pl. [92], figs. 16-18) is distinguished by the possession of six divergent basal feet, probably identical with those of all six-radiate Nassellaria; three of these may be regarded as primary and perradial, the odd caudal and the paired pectoral feet; the three other intercalated as secondary or interradial feet, the odd sternal (z) and the paired tergal feet (t1, t11).
The basal plate of these Cortiniscida exhibits the same important differences as in the preceding Semantiscida, either one, or two, or three pairs of basal gates being developed. But there occur also in some species (mainly in Cortiniscus) only three basal gates, an odd anterior (between the two pectoral feet and a connecting horizontal bar), and two paired posterior (between the two pectoral and the odd caudal foot). It requires further accurate researches to solve the important problem, what the true homologies of these typical basal pores and the separating bars are in the different genera of Semantida. In Semantiscus there are three pairs of basal pores in the horizontal seal, corresponding to those of Semantidium and the radial rods or bars between, these are the basal parts of the six radial feet; therefore the odd caudal foot (t) seems to be the posterior, and the odd sternal foot (z) the anterior prolongation of the basal part of the primary sagittal ring; the two paired anterior or pectoral feet (p1, p11) the prolongations of the coracal rods (e) and the two paired posterior or tergal feet (t1, t11), the prolongations of the scapular rods (g). But it is not yet certain whether these six radial feet and the separating gates of the basal plate are all the same and truly homologous in all six-radiate Nassellaria. In every case the comparative study of the Semantida is of the highest value for the accurate knowledge of the Monopylea.
Synopsis of the Genera of Semantida.
I. Subfamily Semantiscida. Basal ring without typical, regularly disposed basal feet (no cortinar feet). |  | Only two, four, or six basal pores (no dorsal and ventral pores). |  | Two basal pores, | 407. Semantis. |
| Four basal pores, | 408. Semantrum. | ||||
| Six basal pores, | 409. Semantidium. | ||||
| Besides four basal pores, also apical pores or dorsal and ventral pores along the whole ring, | 410. Clathrocircus. | ||||
II. Subfamily Cortiniscida. Basal ring with typical, regularly disposed basal feet (cortinar feet). | | Three basal feet. | One odd caudal foot and two paired lateral feet, | 411. Cortiniscus. | |
| Four basal feet. | Two sagittal and two lateral or pectoral feet, | 412. Stephaniscus. | |||
| Six basal feet. | Two sagittal, two pectoral, and two tergal feet, | 413. Semantiscus. | |||
| I. Subfamily Semantiscida. Basal ring without typical, regularly disposed basal feet (no cortinar feet). | ||||||
| Only two, four, or six basal pores (no dorsal and ventral pores). | ||||||
| Two basal pores, | ||||||
| 407. Semantis. | ||||||
| Four basal pores, | ||||||
| 408. Semantrum. | ||||||
| Six basal pores, | ||||||
| 409. Semantidium. | ||||||
| Besides four basal pores, also apical pores or dorsal and ventral pores along the whole ring, | ||||||
| 410. Clathrocircus. | ||||||
| II. Subfamily Cortiniscida. Basal ring with typical, regularly disposed basal feet (cortinar feet). | ||||||
| Three basal feet. | ||||||
| One odd caudal foot and two paired lateral feet, | ||||||
| 411. Cortiniscus. | ||||||
| Four basal feet. | ||||||
| Two sagittal and two lateral or pectoral feet, | ||||||
| 412. Stephaniscus. | ||||||
| Six basal feet. | ||||||
| Two sagittal, two pectoral, and two tergal feet, | ||||||
| 413. Semantiscus. | ||||||
Subfamily 1. Semantiscida, Haeckel.
Definition.—Semantida without typical basal feet or cortinar feet.