On the top of the head an elegant crest of six elongated, recurved, clavate feathers, of which the webs are deflected.
Some of the species are simple, elongate and clavate bodies.
Capitate: with a head: that type of clavate antenna in which the club is abruptly enlarged at tip and forms a spherical mass.
The name is more appropriate to the African species which are clavate.
They are not globular on the end, as the clavate hairs, but have "saw-like" edge.
The stem is stout, even, or much enlarged at the base so that it is clavate.
The stem is nearly cylindrical, gradually enlarging below so that it is clavate, nearly hollow or stuffed with loose threads.
In addition to the general adaptations described above, it is noteworthy for having both lanceolate and clavate aristiforms.
Frustule in zone view linear, linear-elliptical (in our species), or clavate.
When one extremity of the shell is attenuated, and the other becomes suddenly ventricose or globular, it is said to be clavate.