IDY TE1>t' I- - American Museum of Natural History

1970 NEWELL AND BOYD: PERMIAN BIVALVIA
249
acceleration of anterior margin followed at
maturity by more ventral, infracrescent, or
slightly backward, retrocrescent, growth; resilifers
approximately bilaterally symmetrical.
Measurements of left valve of the holotype:
height, 10.3 cm.; length, 8.3 cm.; dorsal margin,
4.2 cm.
DISTRIBUTION: Wandagee Formation, Byro
Group (late Artinskian), Western Australia.
DISCUSSION: From the American P. (Trematiconcha)
likharevi, new species, the Australian species
differs in its relatively short hinge margin,
subquadrate auricles, and more upright, less
orbicular form. It is more similar to P. Trematiconcha)
sparsicostata (Frebold) from Greenland
(fig. 14D). From that species, wandageensis
differs in its larger size, subquadrate auricles,
and delicate costellae of the right valve.
Pseudomonotis (Trematiconcha) likharevi
Newell and Boyd, new species
Figures 6C, D, 15, 16
SYNONYMY: ?Pseudomonotis laevis Girty, 1909
(unrecognizable), Leonardian, New Mexico
(Newell, "1937" [1938]).
DIAGNOSIS: Shell large, orbicular to bluntly
acuminate, left umbo subdued or prominent,
surfaces marked by irregular growth rugae and,
over mature areas, a few coarse primary costae
bearing scales or subcylindrical spines; posterior
extremity extended in well-developed posterior
lobe.
FIG. 16. Pseudomonotis (Trematiconcha) likharevi Newell and Boyd, new species, San Andres Limestone,
near Artesia, New Mexico; A.M.N.H. 2079. A. Latex cast of holotype, A.M.N.H. No. 28938, exterior of
left valve. B. Latex cast of a paratype, A.M.N.H. No. 28939, interior of left valve. C. Latex cast of a paratype,
A.M.N.H. No. 28940, interior of right valve, showing byssal foramen. A, x 1; B, C, x 0.6.