This genus derives its common name from a fancied resemblance to a miniature triumphal car.
Shell very thin, transparent, symmetrical, convex below, flat above, valves unequal, form tricuspidated, cleft at the sides, open like a cleft anteriorly, and tridentated posteriorly; summit truncated.
Hyalæa tridentata.
Hyalæa cuspidata.
H. tridentata. The three-toothed Hyalæa.
Transparent, horn-coloured, globular; tridentated posteriorly; summit and two posterior sides open; finely striated transversely.
2. Clio. Has no Shell. Two species.
Clio Borealis.
Clio Australis.