The Eucoronida, the third subfamily, are the most important group of the Coronida; their numerous species are much more frequent and more widely distributed than those of the other three subfamilies. They may be derived immediately from the Semantida by the development of a lateral or frontal ring. This remains incomplete in the basal part, whilst the two other rings, perpendicular to it (the vertical sagittal ring and the horizontal basal ring), are complete. Therefore the shell constantly exhibits six large open gates between the three rings; four lateral gates (the same as in the Zygostephanida and Acanthodesmida) and two basal gates (inherited from _Semantis_); the latter correspond to the "jugular pores" of the #Spyroidea# and #Cyrtoidea#; they remain constantly simple. The four lateral gates may also remain simple (_Eucoronis_) or they may become partly closed by irregular loose lattice-work (_Plectocoronis_). The remarkable genus _Podocoronis_ is distinguished by the development of typical descending basal feet, which are regularly disposed and correspond to the typical "cortinar feet" of the other NASSELLARIA. There may be developed either two lateral feet (as lower {969}prolongations of the segments of the frontal ring), or three feet (one caudal and two pectoral, as in _Cortina_ and _Cortiniscus_), or four feet (two sagittal and two lateral, as in _Stephanium_ and _Stephaniscus_), or six feet (two sagittal, two pectoral, two tergal, as in _Semantiscus_), sometimes numerous feet (as in _Petalospyris_ and _Anthocyrtis_, &c.).