ORTMANN : TERTIARY INVERTEBRATES. 
149 
Fam. PSA MM OB I ID AEL Dali. 
Gen. PSAMMOBIA Lam. 
76. PSAMMOBIA PATAGONICA Philippi. 
PI. XXIX, Fig. 4. 
1887 P. pat. Philippi, Tert. and Quart. Verst. Chiles, p. 143, pi. 26, f. 17. 1 
1899 P. pat. v. Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 21. 
Shell elongated-elliptical, compressed, smooth, almost equilateral, the 
posterior end a little shorter, both ends evenly rounded. Anterior and 
posterior dorsal margins straight, forming an obtuse angle. Ventral 
margin very slightly curved. 
Length, 28 mm; height, 16 mm; diameter, 3 (x 2) mm. 
Record of specimens : Mouth of Santa Cruz River, 10 valves; Las 
Salinas, 6 valves ; 30 miles north of upper Rio Chalia, 1 double cast ; 
Arroyo Gio, 3 casts. 
Distribution : Patagonian beds of Santa Cruz (Phil., v. Ih.). 
Affinities : This species has a distinct Eocene appearance, and resembles 
much the forms described by Deshayes (i860, p. 370, ff.) under the names 
of P. nitida (pi. 24, f. 1, 2), and P. tenera (pi. 24, f. 6-8), especially the 
first, with which it also agrees in size. 
A very closely allied species is P. haniiltonensis Tate (1887, p. 167, pi. 
16, f. 13) from Muddy Creek, Victoria, and Table Cape, Tasmania, from 
so-called “Eocene,” but probably Miocene beds. 
Fam. MA C TRI DAE Gray. 
Gen. MACTRA L. 
77. Mactra (?) darwini Sowerby. 
PI. XXIX, Fig. 8. 
1846 M. d. Sowerby, in : Darwin Geol. Observ. S. Amer., p. 249, pi. 2, f. 9. 
Shell triangularly subovate, almost equilateral, compressed, but con- 
vex toward the apex. Surface smooth, with concentric lines of growth. 
1 There are two figures numbered 17 on Philippi’s plate, but only the smaller one represents 
this species, the larger one is Tcllina subfalcata. 
