Abstract
In a recent study of the growth stages of Promicroceras marstonense (Currie, 1942), it was shown that apart from slight individual variations, the growth-ratios exhibited changes at certain stages, which are characteristic of the species. A similar investigation has now been carried out with material representing other species of Promicroceras, in order to ascertain how far there is general agreement within the genus and the extent to which any differences are typical of the various species studied.

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