ORTMANN : TERTIARY INVERTEBRATES. 
151 
There are some species in the Eocene beds of France, which resemble 
this one in outline, although they differ in other respects : M. levesquei 
Desh., M. lamberti Desh., and M. contortula Desh. ( Deshay es, i860, p. 
289, ff. pi. 18). 
Another closely allied form is M. trinacria Semp. (Speyer, 1866, p. 34, 
pi. 3, f. 4) from the Oligocene of northern Germany, but it is smaller and 
a little higher. 
Gen. LUTRARIA Lam. 
79. Lutraria (?) undatoides Ortmann. 
PI. XXX, Fig. 3. 
1899 L. u. Ortmann, in: Amer. Journ. Sci., v. 8, p. 429. 
Shell almost elliptic, i l / 2 times as long as high. Surface with strong, 
and somewhat irregular, undulated concentric folds. Dorsal margin 
almost straight, ventral margin slightly arcuate. Apex at f of the 
length, prominent, rather sharp, incurved. Anterior and posterior ends 
evenly rounded, and of the same height. 
Length, 32 mm; height, 21 mm; apex at 11 mm from anterior end. 
Remarks : Only the remote resemblance to L. undata Phil. (1887, p. 164, 
pi. 33, f. 8-1 1 ) induces me to place this species with the genus Lutraria. 
Record of specimens : Punta Arenas, horizon II (lower Magellanian), 1 
double valve (cast). 
Fam. CORE U LID Ad Flem. 
Gen. CORBULA Lam. 
80. Corbula hatcheri Ortmann. 
PI. XXX, Fig. 4 a ' c . 
1900 C. h. Ortmann, in: Amer. Journ. Sci., v. 10, p. 371. 
Shell small, solid and thick, subovato-triangular. Right valve very 
little larger than left, both moderately convex. Anterior end rounded, 
posterior produced, sub truncate, an angular ridge running down from the 
apex to the posterior angle. Ventral margin arcuate, posteriorly a little 
concave. Lower margin of right valve reflected toward the left valve. 
Surface with concentric ribs, which are rounded and rather crowded. 
