220 ERYCINIDA. 
cies, is viviparous, and lives as much out of the sea as in it, 
Other species occur in various parts of the world.”—JEFFREYs, 
Lepton, Turton. 
Liym.—Lepton, a minute piece of money (from leptos, thin). 
Syn.—? Solecardia (eburnea), Conrad, 1849. 
Distr.—20 sp. Universal. Laminarian and coralline zones. 
Fossil, 5 sp. Eocene—; United States, Europe. DL. squamosum, 
Mont. (exx, 61). 
Shell suborbicular, compressed, smooth, or shagreened, a little 
opened at the ends and longest behind; hinge-teeth 0-1 or 1:1 in 
front of an angular cartilage-notch ; lateral teeth 2-2 and 1-1. 
Animal with the mantle open in front, extending beyond the 
shell, and bearing a fringe of filaments, of which one in front is 
very large; siphon single, gills two on each side, separate ; foot 
thick, tapering, heeled and grooved, forming a sole or creeping 
disk.—ALDER. 
PristopHoraA, Carpenter, 1866. 
Distr.—P. oblonga, Carp. San Diego, Cal. 
Shell oval, with two diverging teeth in each valve, the anterior 
being conspicuously shorter than the posterior, sulcated near the 
beaks, ligament situated in a groove between them. 
Kenia, Turton, 1822. 
Liym.—Named after Mr. O’Kelly, of Dublin. 
Syn.—Cycladina (Adansonii), Cantr. 
Distr.—35 sp. Norway, New Zealand, California. Fossil, 20 
species. Eocene—; United States, Europe. K. suborbicularis, 
Mont. (exx, 92). 
Shell small, thin, suborbicular, closed; beaks small; margins 
smooth ; ligament internal, interrupting the margin (in K. sub- 
orbicularis),or on the thickened margins (in K. rubra) ; cardinal 
teeth 1 or 2, laterals 1—1 in each valve. 
Animal with the mantle prolonged in front into a respiratory 
canal, either complete (in A. suborbicularis) or opening into the 
pedal slit (in K. rubra); foot strap-shaped, grooved; gills large, 
two on each side, united posteriorly, the external pair narrower 
and prolonged dorsally; palpi triangular; posterior siphonal 
orifice single, exhalent. 
The hinges of these little shells are subject to variations, 
which are not constantly associated with the modifications of 
the mantle-openings. They creep about freely, and fix them- 
selves by a byssus at pleasure. XK. rubra is found in crevices of 
rocks at high-water mark, and often in situations only reached 
by the spray, except at spring-tides; other species range as 
deep as 200 fathoms. K. Laperousii (Chironia), Desh., was 
obtained, burrowing in sandstone, from deep water, at Monterey, 
California. 
