. Bulletin of the British Museum (Natural History), Geology. 3o6 MID-TERTIARY CYTHERETTINAE The trends seen in these three species are, therefore: (i) Change from a rounded to a more elongate shape. (ii) Anterior margin from obliquely rounded to evenly rounded. (iii) Development of coarse puncta, especially around the median and ventral ridges. The group of specimens from Le Ruel have a mean L/H ratio of 1-43 and have a more rounded appearance than the English C. forticosta. The specimens from Selsey Bill and Bramshaw are more elongate, with a mean ratio of 1-50. The Whitecliff 0 60 0 55- 0-50
. Bulletin of the British Museum (Natural History), Geology. 3o6 MID-TERTIARY CYTHERETTINAE The trends seen in these three species are, therefore: (i) Change from a rounded to a more elongate shape. (ii) Anterior margin from obliquely rounded to evenly rounded. (iii) Development of coarse puncta, especially around the median and ventral ridges. The group of specimens from Le Ruel have a mean L/H ratio of 1-43 and have a more rounded appearance than the English C. forticosta. The specimens from Selsey Bill and Bramshaw are more elongate, with a mean ratio of 1-50. The Whitecliff 0 60 0 55- 0-50- 0-45 0-40. 0 65 070 075 Length -mm. 080 0-85 Fig. 16. Size distribution of species of the superspecies C. laticosta (Ruess).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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