IV.—The Structure and Function of the Alimentary Canal of some Species of Polyplacophora (Mollusca)

Abstract

The work described in this paper was carried out in the Department of Zoology of Birkbeck College, University of London, and at the Marine Laboratories at Plymouth and Port Erin. I wish to acknowledge my indebtedness to the University of London for the use of their table at Plymouth, to Birkbeck College for a grant of £5 towards the illustrations, and, in particular, I would express my gratitude to Mr Graham, under whose direction the work was carried out, for his continued kindness and help.The specimens ofLepidochitona cinereuswhich were used for the investigation were collected at Bangor, Plymouth and Port Erin, and also obtained from Cullercoats. Most of the material from Plymouth and one specimen from Cullercoats was infected with the Haplosporidian parasiteHaplosporidium chitonis(Debaisieux, 1920) and was therefore unreliable for histological and physiological work. Specimens ofAcanthochitona crinituswere collected at Plymouth, and showed no sign of infection withHaplosporidium chitonis; a few, however, were slightly parasitised with another Sporozoan. The Californian speciesIschnochiton magdalenensisandCryptochiton stelleriwere obtained from Turtox General Biological Supply House, Chicago. Specimens of these species were fixed in formalin, which proved to be a poor fixative for histological work.