Il6 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



Record of specimens : Mouth of Santa Cruz River ; 2 right, i left 

 valves ; San Julian, Darwin Station ; i right, 2 left valves. 



Distribution: Gulf of S. Jorge, Patagonian formation (v. Ih.). 



Affinities: There is a strong resemblance to P. caloosaensis Dall (1898, 

 p. 731, pi. 29, f. 12) from the Pliocene of Florida, but in the latter the 

 striae are stronger, more rib-like, and P. caloosaensis approaches in this 

 respect more the younger individuals of P. proximus. 



The Australian representative of this species is : Pecten palmipes Tate 

 (1886, p. 105, pi. 5, f. 4, pi. 7, f. 4) ; it has been found in so called (?) 

 Eocene beds of Edithburgh, Yorke Peninsula, and of Aldinga Bay (South 

 Australia). 



39. PECTEN CF. CENTRALIS Sowerby. 



PI. XXIII, Fig. i"- 6 . 



1846 P. centr. Sowerby, in: Darwin, Geol. Observ. S. Amer., p. 253, pi. 

 2, f. 31. 



Sowerby figures a left valve. It is characterized by 5 (text, the figure 

 shows 6) radial ribs, which are thin and sharp, and separated by broad, 

 concave intervals. This character is exhibited in our left valve, but the 

 intervals are finely squamulose, without striae, while Sowerby describes 

 "numerous rough radial lines." 



Sowerby did not possess right valves. Our right valve, which was 

 found in connection with the left, agrees completely with that of the fore- 

 going species (P. prcznuncius}. Anterior ear without sinus. 



Both valves are much broken, very delicate, and have been put in a bed 

 of plaster, some fragments of the left valve, however, are not in the proper 

 place ; I give the figures, as is the present condition of the shell. 



Measurements of left valve : Height, ca. 63 mm ; width, ? 



There remains some doubt whether this is really Sowerby's species ; but 

 since it comes from one of his type-localities, it may be that it is this species. 



Record of specimens: Port Desire, N. E. side, i right and i left valve, 

 belonging together. 



Distribtttion : San Julian and Port Desire, one fragment from the first 

 locality, two of the latter (Sow.). Sowerby and Darwin (1846, p. 113) 

 mention this species also from Santa Cruz. 



