A Note on the Growth Stages and Structure of the Adult Lophophore of the Brachiopod Terebratella (Waltonia) Inconspicua (G. B. Sowerby)

Certain of the growth stages of the lophophore of Terebratella (Waltonia) inconspicua (Sowerby), from a shell length of 0.55 mm., are described and figured, so as to elucidate the position of the mouth and the mode of development of the lip of the food groove. The mouth is a small aperture in front of the bases of the first formed pair of filaments. The lip of the food groove is formed by lateral growth from a small preoral lobe. The early lophophore (trocholophous and early schizolophous) is of the broad‐based terebratellacean type set low on the dorsal mantle, and the filaments when extended in feeding are directed anteriorly and ventrally. The structure of the adult lophophore is described. The ciliary feeding mechanism is essentially similar to that described by the author in Macandrevia cranium (Müller) and other brachiopods with plectolophous lophophores.