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both Ds - grooved spine; D1 < D2D1 origin behind pectoral free rear tipC: asymmetric, top lobe notched; tail base no keeltop teeth: 1 large + small side pointsno Abelly - usually light organs
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both Ds - grooved spine
D1 = / > D2D1 origin over/behind pectoral baseC v asymmetrical, notch under top lobe, base no keeltop & bottom teeth dissimilar, top << bottomno A -
head narrow, conical
large spiraclesDs small, rounded, usually no spine, D1 < / = D2top teeth - narrow needles, bottom - broad bladesno A -
both Ds: ungrooved spineC: base keeled, asymmetric, large lower lobe, top lobe not notchedtop & bottom teeth similar: blade with one oblique pointno A