The most important of these apophyses of the ring are the basal spines, arising from its basal pole, where the porochora of the central capsule rests upon it. They are often much larger and more branched than the other spines, and attain a peculiar morphological value in the small subfamily Cortinida. Here we find three or four regularly disposed "basal spines," which may be compared to the typical "basal feet" of the #Cyrtellaria#, appearing in the majority of #Spyroidea# and #Cyrtoidea#. _Cortina_, one of the most important NASSELLARIA, bears three typical divergent feet on the base of the simple ring, two paired anterior or "pectoral feet," and an odd posterior or "caudal foot." The latter appears as a direct basal prolongation of the dorsal rod of the ring, and is opposed to an upper prolongation of the same, which corresponds to the "apical horn" of the #Cyrtellaria# (Pl. 97, figs. 1-3). As already explained above, these three basal feet of _Cortina_ possess the highest phylogenetic value, since they may also be compared with the three primary radial spines of the #Plectoidea#, and so connect the #Cyrtellaria# and the #Plectellaria#. _Stephanium_ differs from _Cortina_ in the possession of four basal feet, an odd anterior or "sternal foot" being added to the three typical feet of the latter (Pl. 92, figs. 20, 21). Some forms of #Plectoidea# (_Plagoniscus_, _Plectaniscus_, &c.) seem to be nearly related to these Cortinida, and may be easily transformed into them by development of a complete ring, embracing the central capsule. They seem to demonstrate the near affinity of all these triradiate NASSELLARIA (Pl. 91, figs. 4, 5, 9, 10). {940}_Synopsis of the Genera of Stephanida._ ------------------------------------------------------------------------- I. Subfamily Lithocircida. No typical basal feet on the base of the ring (no cortinar feet). ------------------------------------------------------------------------- Ring diphragmatic or { Ring smooth or thorny, amphithect; dorsal { without branched spines. 401. _Archicircus_. and ventral bow { equal. { Ring armed with branched { spines, 402. _Lithocircus_. Ring dipleuric, { Ring smooth or thorny, bilateral; dorsal { without branched spines, 403. _Zygocircus_. and ventral bow { different. { Ring armed with branched 404. _Dendrocircus_. { spines. ------------------------------------------------------------------------- II. Subfamily Cortinida. Three or four typical basal feet on the ring (cortinar feet). ------------------------------------------------------------------------- Three basal feet (and { One caudal and two lateral an apical horn). { feet, 405. _Cortina_.