A full complement of fins is rarely present, but a
primordial fin fold was well developed in the sagittal
plane. The primordial fin being fairly soon replaced
by median fins helps in locomotion. The yolk sac was
ovoid in addition to 20% the total body length.
Mouth and anus were not yet opened but alimentary
tract was distinct. The circulatory function was
totally established (Fig. 2d).