220
Fig. 2.64 Schematic hypothetical sequence of integrated frontal-shield
and ooecial evolution (developing or fully formed calcifi ed parts stippled): ( A1 ) cribrimorph with frontal kenozooids and developing fold of
calloporiform ooecium. ( A2 ) Spinocystal umbonulomorph ancestor
with frontal kenozooidal overgrowth and calloporiform ooecium.
( B ) Umbonulomorph with lepralielliform ooecium. ( C ) Umbonulomorph
with developing fold of calloporiform ooecium. ( D ) Umbonulomorph
with escharelliform ooecium. ( E ) Lepraliomorph with calloporiform ooecium. ( F ) Lepraliomorph with lepralielliform ooecium. ( G ) Lepraliomorph
with escharelliform ooecium. Abbreviations: as ascus, ec ectooecium, en
entooecium, ep epistege, fo ooecial fold, fr frontal shield, fw non-calcifi ed
frontal wall, g gymnocyst, k frontal kenozooid, of ovicell fl oor
2 Cheilostome Brood Chambers: Structure, Formation, Evolution
Fig. 2.64 Schematic hypothetical sequence of integrated frontal-shield
and ooecial evolution (developing or fully formed calcifi ed parts stippled): ( A1 ) cribrimorph with frontal kenozooids and developing fold of
calloporiform ooecium. ( A2 ) Spinocystal umbonulomorph ancestor
with frontal kenozooidal overgrowth and calloporiform ooecium.
( B ) Umbonulomorph with lepralielliform ooecium. ( C ) Umbonulomorph
with developing fold of calloporiform ooecium. ( D ) Umbonulomorph
with escharelliform ooecium. ( E ) Lepraliomorph with calloporiform ooecium. ( F ) Lepraliomorph with lepralielliform ooecium. ( G ) Lepraliomorph
with escharelliform ooecium. Abbreviations: as ascus, ec ectooecium, en
entooecium, ep epistege, fo ooecial fold, fr frontal shield, fw non-calcifi ed
frontal wall, g gymnocyst, k frontal kenozooid, of ovicell fl oor
2 Cheilostome Brood Chambers: Structure, Formation, Evolution