The Alimentary Canal of Marinogammarus Obtusatus (Crustacea, Amphipoda)

The functional morphology of the alimentary canal of Marinogammarus obtusatus Dahl is described, with particular reference to the proventriculus and the digestive gland. The proventriculus is a device (1) for the mastication of food, (2) for retaining it while it is being broken up and acted upon by enzymes and (3) in which provision must be made to convey enzymes forward into the cardiac region and digested food backwards to the digestive gland. Finally, there must be a valvular device to direct undigested food past the ducts leading to the digestive gland and into the intestine. The proventriculus of M. obtusutw. is compared with that of mysids and isopods and it is concluded that modifications of the fore‐gut in various lacostracan groups are likely to be adaptations to diflerences in food and feeding habits There is no clear functional distinction between the so‐called secretory and reserve cells of the digestive gland, both of which secrete enzymes, absorb and store food.