The observations presented by Mr. J. Wilfrid Jackson (1916) on my paper on “Brachiopod Morphology”, published in this Magazine in 1915, are very welcome as furnishing many important details omitted by Davidson and other writers in the description of species. The error into which I fell as regards the types of folding of Dallina and Dalinella illustrates the danger of relying on figures when specimens are not available, but it was worth while making such an error when the correction of it brought forward so many useful observations on other points, particularly on the prevalence of dental plates in the Dallininæ and the relationships of Mühlfeldtia. These observations pave the way for a further advance in the natural or genetic grouping of species and genera. At the same time, while admitting that Dallina is ventrally biplicate, I am not disposed to agree with Mr. Jackson that the folding is exactly comparable to the ventral biplication exhibited in some species of Magellania, but probably arose in a different way. I refrain from a further statement on this point, as I understand that Mr. S. S. Buckman is discussing the subject of types of folding fully in his forthcoming memoir on the Jurassic Brachiopods of Burma. In what follows I shall have again, through lack of specimens in Colonial museums, to rely on figures to some extent, and may possibly again err from this cause, and if so hope the correction will be applied as promptly and informatively as in the former case.