13 DISCOVERY REPORTS 



The similarity of the Burdwood Bank and Trinidad faunas is more readily understood 

 when the rather deep-water facies of both is taken into account. 



The widespread similarity of the Foraminifera is strikingly in keeping with the re- 

 sults obtained from a study of the Senonian ammonites of the South Patagonia-Graham 

 Land region as noted below, while the Upper Senonian MoUusca are said to be similar 

 to those of New Zealand.^ The Tethys, according to Gregory,^ had, in the Upper 

 Cretaceous, perhaps its widest extension. It ranged during the Middle Senonian 

 " from Kansas to England, Algeria, southern India, and to the Gingin Chalk of Western 

 AustraUa, On the other side of the Pacific the European fauna reached northern Chile 

 (23° S), doubtless through the West Indies . . . ". Since the south Atlantic region appears 

 to have been largely occupied by land at this period^ the connection between the Senonian 

 sea over the Mexican and South Patagonia-Graham Land regions must have lain to the 

 west of the present South America.* 



Of the Burdwood Bank fossil Foraminifera other conspicuous species are Cyclammina 

 conceUata, C. orbicularis and Ammodisciis incertus. These three, with seven other species 

 of the complete list above, have been recorded by Nuttall from the Tertiary (Upper 

 Eocene to Middle Miocene) of Trinidad.^ Nuttall's material is preserved in the Sedg- 

 wick Museum in Cambridge, and I have checked the agreement of his specimens with 

 those from the Burdwood Bank. Certain of these species, particularly of Cyclammina, 

 are common forms of the Trinidad tertiaries, and, taken into consideration with the 

 regional stratigraphical development, may point to strata of similar age exposed on the 

 Burdwood Bank. These arenaceous species can, however, be regarded only as evidence 

 of similar facies, and not of age. Of a total of some 300 specimens of Foraminifera 

 mounted there are at least eighty-six specimens referred to Cyclammina spp., so that 

 it is a common genus, only approached in numbers in the collection by Haplophrag- 

 moides spp., of which there are at least thirty-five specimens, and Ammodisciis with 

 twenty-seven. It may be noted, however, that these are all rather large forms found 

 loose on the sea-bottom, and it is likely that they have been preserved owing to their 

 size and stout build when smaller forms have been destroyed or removed. 



The crushed state of many of the specimens, particularly of arenaceous species, is a 

 feature which has been remarked by Cushman and Jarvis in the Trinidad Cretaceous 

 (1928, loc. cit., p. 85), and by Nuttall in the Trinidad Tertiary (1928, loc. cit., p. 70). 

 I have observed a severely crushed foraminiferal fauna from the Tertiary of Ecuador 

 (Clay Pebble Bed of Ancon), and there are many badly crushed specimens in the fauna 

 from the Clay of Payta, North-west Peru. 



^ Cf. J. W. Gregory, 1930, Proc. Geo!. Soc, p. xcviii. 

 ^ Loc. cit., p. xciv. 



^ See Gregory, 1929, Proc. Geol. Soc, p. cxviii, etc.; and von Ihring, 1931, Quart, jfoiirn. Geol. Soc, 

 Lxxxvii, p. 386, etc. 



* See also A. Windhausen, 1932, Zeitschr. Ges. Erdkuiide, Berlin, p. 28, text-fig. 2. 

 ^ 1928, Quart. Journ. Geol. Soc, lxxxiv, pp. 57-115, pis. iii-viii. 



