The alimentary canal of centipedes is a straight tube which is clearly divided into fore-gut, mid-gut and hind-gut. The fore-gut originates as an ectodermal invagination, the stomodaeum, and hence is lined by cuticle. It comprises the pharynx and oesophagus, the latter sometimes differentiated into crop and gizzard or proventriculus. The mid-gut is of mesodermal origin (mesenteron) and the hind-gut is formed from a posterior ectodermal invagination, the proctodaeum. A pair of Malpighian tubules originate at the junction of the mid- and hind-gut and run forwards towards the head (Figs. 110, 111). They are described in Chapter 16. The so-called ‘salivary glands’ are described in Chapter 15.

The pre-oral cavity is bounded anteriorly by the labrum, anterodorsally by the membranous epipharyngeal surface, laterally by the mandibles and ventrally by the anterior portion of the hypopharynx, a delicate lobed structure which usually bears dense fields of hairs and the pores of unicellular glands. The mouth opens into the pharynx.

Geophilomorpha

The epipharynx is very poorly developed in geophilomorphs and the hypopharynx is reduced to a small bilobed structure covered with fine hairs. The pharynx is very short, its wall showing lateral longitudinal thickenings to which are attached the pharyngeal dilator muscles (Fig. 112) (Verhoeff, 1902–25).

The alimentary canal posterior to the pharynx has been described for Haplophilus subterraneus gervaisi (Plateau) and Necrophloeophagus longicornis (Fig. 110a) by Plateau (1878). The oesophagus is long and narrow, its folded cuticular lining lacking spines.