To the right (in the figure) of the rectal peduncle is seen the deeply invaginated shell-gland ss, with a secretion sh protruding from it.
Two pairs of muscles, apparently connected with the peduncle and its limited movements, have been minutely described by Hancock as having one of their extremities attached to this organ.
The dorsal adjustors are fixed to the ventral surface of the peduncle, and are again inserted into the hinge-plate in the smaller valve.
The function of these muscles, according to the same authority, is not only that of erecting the shell; they serve also to attach the peduncle to the shell, and thus effect the steadying of it upon the peduncle.
The first antennae have a lamellar appendage at the end of the peduncle, a decidedly non-entomostracan feature.
