Peniagone

Théel, 1886

38 species

Body more or less elongate, anterior end often more or less neck-like, prolongated. Tentacles 10; lateral tube not united by a web except sometimes a few at the posterior end. Dorsal papillae only at anterior end forming a raised fan-like prominence. Calcareous deposits mainly four armed bodies with 1 to 4 outwardly directed processes. (Mortensen, 1927)

Lateral feet more or less numerous, sometimes absent on the part of the ambulacra which is nearest the mouth. Distinct nuchal thickening with 2 anterior pairs of papillae, which are either free or united by a larger or smaller web of a veil; 1 or 2 posterior pairs of atrophying papillae may be present behind the veil. Deposits derived primarily from crosses with 4 more or less strongly inward bent arms and 4 outer, short to long projections; deposits smooth or covered with fine spines. (Deichmann, 1930)

Dorsal papillae anteriorly placed, usually forming a velum. Deposits primary crosses, or cross-shaped. Calcareous ring consisting of 5 isolated pieces, each having a varying number of arms. (Hansen, 1975)