On the Ciliary Mechanisms and Interrelationships of Lamellibranchs: PART IV: Cuticular Fusion, with special reference to the Fourth Aperture in certain Lamellibranchs

Abstract

A form of fusion involving only the cuticle has been found in certain Lamellibranchs between the outer demibranchs and the mantle or the visceral mass; between the two inner demibranchs; and, in forms possessing a fourth aperture, between the mantle lobes in the mid-ventral line between this and the pedal aperture. The histological structure of the junction is described, and is especially considered in relation to the condition of the fourth aperture in the Solenidae.