VI.—Brachiopod Morphology: Notes and Comments on Dr. J. Allan Thomson's Papers

Abstract

From a long and careful study of the Brachiopoda I am led to offer some observations upon the two recently published papers by Dr. J. Allan Thomson which have appeared in this Magazine. In the case of Dallina I cannot agree with Dr. Thomson regarding the type of folding. He considers D. septigera (the genotype) and D. raphaelis as dorsally biplicate, D. floridana as dorsally uniplicate. Now dorsal biplication is brought about by the dorsal sulcus being superimposed upon a single dorsal fold. In D. septigera, as well as in D. floridana, a broad ventral sulcus is superimposed upon a dominant ventral fold; these two species, therefore, are, in my opinion, ventrally biplicate (as in Magellania flavescens and some others).