IIO PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



hatclteri. The more oval specimens are fully identical with Philippi's main 

 figure of O. bourgeoisi. These specimens approach closely the Cape Fair- 

 weather form in the triangular outline, moderate area, and medium size 

 and thickness of the shell. 



23. Cape Fairweather ; 23 double, 1 2 lower, 5 upper valves. 



The characters of this form are given above. Crenulations of the mar- 

 gin, close to the area (see pi. XVIII, fig. i*), are shown in 14 upper 

 valves (out of 28). 



Thus we possess from these 23 different localities 77 double, 76 isolated 

 lower, and 35 isolated upper valves. Altogether, 153 lower, and 112 

 upper valves are represented in our collection. 



Distribution: Darwin mentions this species from southern Patagonia 

 generally, Philippi from Punta Arenas, v. Ihering from Santa Cruz and 

 La Cueva (upper part of Patagonian formation and Suprapatagonian 

 respectively); it has been found in the Pliocene Coquimbo beds of Chile 

 (Moer.), and further in New Zealand, in the Oamaru and Pareora beds 

 (Oligocene and Miocene) (Zitt, Hutt). 



Affinities: Moericke has already compared this oyster with O. crassis- 

 sima Lamck. from the Miocene of Europe, and there is no doubt a strik- 

 ing resemblance between them in general appearance. Still closer appears 

 the relation to that form called O. gingensis (Schloth.), especially when we 

 compare the account and figures given of it by Hoernes (1870, p. 452, pi. 

 76-80). Hoernes (p. 455) points out the close resemblance of O. gin- 

 gensis and ingens. 



This type of oyster (cmssisst'ma-type) although not exclusively found 

 in the Miocene is a very characteristic feature of Miocene deposits. In 

 older Tertiary beds this giant type is not found. 



35. OSTREA PATAGONICA d'Orbigny. 

 PI. XX, Fig. i**. 



1842 O.patagonica d'Orbigny, Voy. Amer. merid., v. 3, p. 33, pi. 7, f. 14-16. 



1842 O. ferrarisi d'Orbigny, ibid. 



1887 O. patagonica Philippi, Tert. Quart. Verst. Chiles, p. 215 (part), pi. 



48, f. 2 (after d'Orbigny). 

 1887 O. ferrar. Philippi, ibid., pi. 48, f. 5 (after d'Orbigny) (non text, 



p. 214). 



