Leptopentacta

Clark, 1938

13 species

Body elongate, slender, pentagonal curved, firm body wall with enlarged scales or plates covered with densely calcified epidermis, pedicels few in single straight or zig-zag series and in double series in ventral ambulacrum tentacles 10 small, ventral pair smaller. (Clark, 1938)

Slender forms with curved body, ambulacra forming 5 indistinct ridges. Feet scattered in double rows in the middle portion of the ambulacra, towards the end in single rows, around the base of the introvert forming 5 large valves as in Pentacta. Tentacles 10, bushy, the 2 ventral smaller. Surface of skin rough numerous spine-like projections on the spicules piercing the skin. Calcareous ring with short posterior projections. Spicules consisting of an external layer of strongly knobbed 4 holes buttons with minute holes and smaller buttons, less strongly knobbed and with larger holes and numerous 4 spoked baskets. in an inner layer of reticulated ovoid or spherical grains. Feet possibly with an end plate not yet discovered, numerous perforated supporting plates, and the same type of spicules as in the integument. Particularly numerous in the appendages though also present in the skin are some peculiar oblong heavy plates with small holes and one end drawn out into a shorter or longer spine which pierces the skin. Introvert with rosettes, tentacles with large curved perforated plates and rods, also rosettes, and the finer branches, delicate rods with perforate ends. (Deichmann, 1941)

Body slender, 5 cornered, curved. The skin stiff (rigid). The mouth has 5 flaps. There are ambulacra appendages only in the radii in 1 or 2 rows. There are 10 tentacles. The calcareous ring is simple, undivided, to the rear it is deeply incised, fork tail fashion. The calcareous deposits: to the surface there are cups. Deeper in the skin there are large scales. These are, in one group, deeply vaulted, constructed from several layers of network, then not arranged roof tile fashion, but rather packed over each other like stones of a wall; in small animals, they are even one layered, massive with smooth surface and then covering each other roof tile fashion. Smaller plates lay on the scales on in the gaps between them, occasionally also on their underside. These plates are smooth or covered with bumps. (Panning, 1966)