(Table 4) Distribution of Albian-Cenomanian nannofossils in DSDP Hole 77-540

Species abundances: V = very abundant (> 10 specimens per field of view at 1560 X), A = abundant (1 to 10 specimens per field), C, common (1 specimen per 2-10 fields), F = few (1 specimen per 11-100 fields), R = rare (1 specimen per 101-1000 fields). - = absent.物种丰度分级标准如下：V=极丰富（very abundant，1560倍放大视野下每视野标本数＞10）；A=丰富（abundant，每视野1~10个标本）；C=常见（common，每2~10个视野出现1个标本）；F=稀少（few，每11~100个视野出现1个标本）；R=稀有（rare，每101~1000个视野出现1个标本）；-=缺失（absent）