------------------------------------------------------------------------- I. Subfamily Zygostephanida. Four lateral gates (no basal gate). ------------------------------------------------------------------------- Two meridional rings }Four lateral gates (sagittal and frontal) } simple, 414. _Zygostephanus_. complete, perpendicular } to one }Four lateral gates another (no basal } partly latticed, 415. _Zygostephanium_. ring). ------------------------------------------------------------------------- II. Subfamily Acanthodesmida. Five large gates (four lateral and one simple basal). ------------------------------------------------------------------------- Two meridional rings }Four lateral gates (sagittal and frontal) } simple, 416. _Coronidium_. incomplete, both } truncated by the }Four lateral gates complete horizontal } partly latticed, 417. _Acanthodesmia_. basal ring. ------------------------------------------------------------------------- III. Subfamily Eucoronida. Six large gates (four lateral and two basal). ------------------------------------------------------------------------- Two rings (the {Basal ring {Gates simple, 418. _Eucoronis_. sagittal meridional{ without larger{ ring and the { descending {Gates partly horizontal basal { feet. { latticed, 419. _Plectocoronis_. ring) complete, the{ frontal meridian {Basal ring with large, ring incomplete. { regularly disposed, { descending feet. Gates { simple, 420. _Podocoronis_. ------------------------------------------------------------------------- IV. Subfamily Trissocyclida. Eight large gates (four upper lateral and four lower basal). ------------------------------------------------------------------------- Two meridional {Four upper {Gates simple, 421. _Tristephanium_. rings (sagittal and{ gates larger { frontal) and the { than the {Gates partly horizontal basal { four lower. { latticed, 422. _Tricyclidium_. ring complete. All { three complete {All eight gates{Gates simple, 423. _Trissocircus_. rings perpendicular{ of equal size.{ to one another. { {Gates partly {latticed, 424. _Trissocyclus_. Subfamily 1. ZYGOSTEPHANIDA, Haeckel, 1881, Prodromus, p. 446. _Definition._--#Coronida# with four large lateral gates, without basal gate. Skeleton composed of two complete vertical rings, perpendicular one to another--the primary sagittal and the secondary frontal ring. Genus 414. _Zygostephanus_,[33] Haeckel, 1862, Monogr. d. Radiol., p. 268.