ORTMANN : TERTIARY INVERTEBRATES. 113 



Gen. GRYPH^EA Lamck. 

 36. GRYPH^EA CF. TARDA Hutton. 



PI. XIV, Fig. 4"-'. 



1873 G. tard. Hutton, Catal. Tert Moll. Ech. New Zealand, p. 35. 

 1886 G. tard. Tate, in: Tr. R. Soc. S. Australia, v. 8, p. 98, pi. 6, f. 2. 



Lower (left) valve ovate-triangular in outline, tumid, with incurved 

 umbo. Exterior smooth, with concentric lines of growth ; posterior margin 

 produced into a distinct lobe. 



Height, 59 mm; width, 58 mm (but posterior lobe-like expansion 

 damaged). 



Remarks: According to Tate, G. tarda is very close to the European 

 and North American upper Cretaceous G. vesicularis (Lamck.), and differs 

 chiefly in the more triangular outline and larger lobation. Especially the 

 first character would apply to our specimen, which agrees well also in the 

 side view with Tate's figure. Our specimen, however, does not possess 

 the upper valve, the inner side of the lower is filled with hard matrix and 

 not exposed, and further, the lobe-like expansion of the posterior margin 

 is much damaged. Thus it is hard to say, whether our Patagonian fossil 

 is really identical with the Australian species or not. The close resem- 

 blance to O. vesicularis is quite striking, and there is hardly any doubt 

 that we have to deal with a species of the genus Gryphcza. 



Record of specimens : High bluffs, S. W. of Lake Pueyrredon, ca. 1000' 

 below Santacruzian beds, i sp. 



Distribution: G. tarda has been mentioned first by Hutton from the 

 Chatham Islands, from beds, which belong probably to the Oamaru and 

 Pareora series (Oligocene and Miocene). Tate records this species from 

 South Australia (Aldinga Bay and Bunda Cliffs) from supposed Eocene 

 beds (lowest beds of marine series of older Tertiary). 



The genus Gryphcea is generally supposed to have disappeared at the 

 close of the Cretaceous period, but we must bear in mind that already 

 Whitfield (1885, p. 224) has recorded G. vesicularis from the Eocene 

 marls of New Jersey, and according to Zittel (1885, p. 20) it continues 

 to Recent times. The stratigraphical position of our specimen is not 

 very well ascertained, but it has been found associated with a number of 



