12 
PATAGONIAN EXPEDITIONS : PALEONTOLOGY. 
These Chilean specimens are distinctly exogyrate and have very little re- 
semblance to the Patagonian form. In a later work byCoquand 1 they 
are referred to Ostrea aquila, which is also made to include Exogyra im- 
bricata Krauss, a similar form from the Uitenhage beds of South Africa. 
A species that resembles O. tardensis more closely than those above 
mentioned has been described by Stoliczka 2 under the name Gryphcea 
ariana from the Arrialoor group of the Indian Cretaceous. Judging from 
the figures the principal difference is in the somewhat less strongly curved 
form of G. ariana. 
It is possible, though I think not probable, that the Patagonian Ostrea 
here described as new is specifically identical with some of the South 
American forms that have been referred to Exogyra couloni, but even if 
that should prove to be true, the identification of that species is believed 
to be erroneous in those cases and a new name is necessary. 
Locality and position. — Mouth of canon of Rio Tarde, four miles east 
of Lake Pueyrrydon, from a horizon (Gio beds) 400 feet below the Ammo- 
nite layer. 
Lima sp. 
Shell small, ovate, slightly oblique, convex with prominent beaks and 
small inconspicuous ears ; surface marked by about 15 rather prominent 
radiating ribs about equal in width to the interspaces, each of which bears 
a fine line. The anterior and posterior portions of the shell not covered 
by the ribs also bear a number of fine radiating lines and show irregular 
lines of growth. 
The three imperfect specimens in the collection are probably immature, 
the largest measuring only seven millimeters in length and five milli- 
meters in breadth. 
Locality and position. — From the Ammonite (Belgrano) beds at mouth 
of canon four miles east of Lake Pueyrrydon. 
Pecten (Camptonectes) Pueyrrydonensis sp. nov. 
Pi. IV, Fig. 1. 
Shell of medium size, ovate or subcircular in outline, moderately con- 
vex ; right valve with unequal ears, the anterior one much larger, trian- 
1 Monographic du Genre Ostrea, p. 158. 
2 Cretaceous Fauna of S. India, vol. 3, p. 465, pi. 43, figs. 2, 2 a , pi. 44, figs. 1-3. 
