The foregut has been variously called the "stomodaeal apparatus" (ponderous, but technically correct); the "stomach" (morphologically incorrect: it is part of the stomodaeum); the "proventriculus" (derived from analogy with insects, where it is a region between the crop and midgut) (Dall W. et al., 1990).

The labrum and surrounding tissues are glandular, but the role of these glands is unknown. The mouth leads into a short vertical oesophagus, surrounded by contractile muscles, which can close it in a sphincter-like manner. The oesophagus opens into the lumen of the anterior of the proventriculus. The proventriculus is divided into two principal chambers. The anterior chamber is distensible, particularly in the anterior part; it is sometimes called the "food sac". There are a pair of ventro-lateral, elongate plates, each of which bears a row of small teeth, which lead to the much heavier armature of the lateral teeth of the gastric mill and the single, dorsal median tooth. The posterior chamber is much narrower than the anterior chamber and is further divided into an upper compartment, which is a through-canal to the midgut, and a lower filter-press. The foregut cuticle ends where the latter opens ventrally into the digestive gland, which surrounds the lower posterior chamber and extends dorsally around it as far as the tip of the anterior diverticulum. Above the filter-press, the foregut cuticle extends backwards to the paired openings of the anterior diverticulum of the midgut, which are closed by a pair of lappets. The principal functions of the midgut are the secretion of digestive enzymes and absorption of nutrients. The remainder of the midgut is a straight tube, running from the cephalothorax dorsally through the abdomen to the rectum. It is lined by a folded, simple epithelium. At the anterior end, two lateral openings lead into the dorsal anterior diverticulum; at the posterior end, a dorsal opening leads into the posterior diverticulum. Histologically both diverticula appear to be simple extensions of the midgut. The short muscular rectum is lined by six pad-like ridges, whose primary function appears to be for grasping the faecal pellet in the peritrophic membrane and extruding it (Dall W. et al., 1990).