ORTMANN : TERTIARY INVERTEBRATES. 
113 
Gen. GRYPHZEA Lamck. 
36. Gryphcea cf. tarda Hutton. 
PI. XIV, Fig. 
1873 G. tard. Hutton, Catal. Tert. Moll. Hch. 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. vesimlaris is quite striking, and there is hardly any doubt 
that we have to deal with a species of the genus Gryphcea. 
Record of specimens: High blufts, S. W. of Lake Pueyrredon, ca. iooo' 
below Santacruzian beds, 1 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 
