E.S.C.O.N.I.

ambulacrum: area of theca containing the food-grooves, side plates, brachioles, and exposed portion of lancet plate

anispiracle: enlarged opening at summit formed by the coalescing of anal opening and posterior spiracle(s)

anthus (crown): composed of theca and brachioles

azygous basal plate: smallest basal plate (1)

brachiolar facet and socket: depressions on side plate of ambulacrum where brachiole articulates to the theca

brachiolar groove: food-groove in ventral surface of brachiole covered by movable plates

brachiolar pit: junction between brachiolar groove and side food-groove

brachiole (pinnule): food gathering appendage attached to sides of ambulacrum

columnal: individual segment of stem

cover plates: small plates that roof all food-grooves, brachiolar grooves, spiracles, mouth, and anus

deltoid plate: interradial subtriangular plate near summit

fissiculate: having exposed or partly exposed hydrospire slits

hydrospire: infolded thin-walled calcareous structure on either side of ambulacrum used for respiration and possibly reproduction

hydrospire fold: thin calcareous wall surrounding hydrospire

hydrospire pore: minute rounded opening near margin of ambulacruni leading into hydrospire

hydrospire slit: longitudinal opening of hydrospire fold excavated in deltoids and radials parallel to and on either side of ambulacrum

lancet plate: elongate spear-shaped plate extending from tip of ambulacrum to summit along the mid-line of ambulacrum and containing the main food-groove

length-width ratio: length of theca divided by width of theca

lumen: small round opening in center of columnal

main (median) food-groove: longitudinal depression extending length of mid-line of ambulacrum leading to summit

oral opening: pentagonal opening at summit of theca marking the position of the mouth

pelvis: portion of theca from tips of ambulacra to stem attachment

peristome: area of oral plates around oral opening at summit

radial plate: one of 5 cleft plates above basal circlet containing part of ambulacrum

side (lateral) food-groove: one of many short, transverse depressions in ambulacrum that begin at the brachiolar pit and empty into the main food-groove at an oblique angle

side plate: plate at edge of ambulacrum containing the brachiolar facet and socket

spiracle: opening in summit which is part of the water vascular system

spiracular slit: elongate spiracle at side of ambulacrum excavated in adjoining radial and deltoid plates

spiraculate: having spiracles

summit: top of theca; location of spiracles, mouth, and anus

summit plates: oral and accessory oral plates

stereome: calcareous tissue in the endoskeleton

theca (calyx): skeletal structures including hydrospires but not including brachioles, stem, or holdfast

vault: portion of theca from tips of ambulacra to summit

vault-pelvis ratio: height of vault divided by height of pelvis

zygous basal: large basal plate (2)

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Last Updated 1/28/2002