ClipArt ETC
"Ventral surface of disc of an Ophiuroid (Ophiothrix fragilis). g., Openings of genital pockets or bursae; m., mouth; v., ventral plates of arms; sp., spines of arms; tf., tube-feet--at the right side these are represented as retracted; o., the opening through which they are protruded; p., plates around mouth bearing the so-called teeth; one of these plates is perforated, and functions as the madreporite." -Thomson, 1916

Ophiuroid

"Ventral surface of disc of an Ophiuroid (Ophiothrix fragilis). g., Openings of genital pockets or bursae;…