Bulletin - United States National Museum - Smithsonian Institution

- SOUTH
AFRICAN MARINE MOLLUSKS. 209
Good Hope. Cat. No. 17496, U.S.N.M., one specimen from the Cape
of Good Hope. Cat. No. 186944, U.S.N.M., one specimen from Port
Alfred (Coll. No. 314).
Genus EASTONIA Gray.
EASTONIA AFRICANA, new species.
Plate 43, figs. 5, 6.
Shell broadly oval, thin. Umbones about one-third of the length
of the shell posterior to the anterior margin. Surface marked by
many slender, raised, radiating threads which are less strong on the an-
terior portion than on the posterior and also much more closely spaced
here than on the posterior part, except the extreme posterior portion,
on which they are entirely absent. The spaces between these ribs
are concaved and marked by very slender, irregular, slanting lines
which give this portion of the shell a crinkly appearance. In addi-
tion to this sculpture, the whorls are marked by numerous feeble
lines of growth.
The type, Cat. No. 186946, U.S.N.M., comes from Port Alfred
(Coll. No. 316), and measures: Length, 36 mm.; altitude, 30 mm.
This is probably what has been reported as Standella solandri Gray,
a species occurring in the Moluccas. It differs from that species in
being shorter and higher and in having many more ribs.
Genus MACTRA Linnaeus.
MACTRA AEQUISULCATA Sowerby.
Cat. No. 128350, U.S.N.M., one specimen from South Africa.
MACTRA ADANSONI Philippi.
There are four lots of this species in the collection of the United
States National Museum, all from Port Alfred, as follows: Cat. No.
187166, two specimens (Coll. No. 713); Cat. No. 187167, one valve
(Coll. No. 714); Cat. No. 251016, two additional valves (Coll. No.
1533); Cat. No. 251033, a very young valve (Coll. No. 1550).
MACTRA ALFREDENSIS, new species.
Plate 44, figs. 6, 7
Shell oval, compressed. Anterior dorsal margin passing in an
almost straight line from the umbones to the extreme anterior por-
tion, and then curving evenly to the evenly curved base. Posterior
dorsal margin more feebly curved. Two radiating raised lines pass
obliquely backward from the umbones; the second of these is a little
more distant from the first than that is from the dorsal margin. The
space inclosed by them is marked by numerous indistinct reticula-