The Echinoid Directory

Fasciole arrangements

Peripetalous fasciole

On aboral surface, running round the ends of the petals

Lateroanal fasciole

Running from behind the anterior petal and passing laterally beneath the periproct. Always associated with a secondary peripetalous element

Internal fasciole

Bounding the anterior ambulacrum but not the paired petals

Subanal fasciole

At the rear of the plastron immediately beneath the periproct. Either lozenge-shaped or bilobed

Lateral fasciole

Passing around the ambitus and beneath the anus at some distance from the tips of the petals

Pseudolateral fasciole

Ambital in position but passing above the periproct and thus a modified peripetalous fasciole