^{page 167 note 1} It will be noticed that we divide the fore-gut into more parts than is usual, this being merely a matter of convenience. In insects the alimentary canal may be divided into three main divisions, in accordance with their embryonic origin, viz. fore-gut, mid-gut, and hind-gut; derived respectively from the stomodaeum, mesenteron, and proctodaeum. The fore-gut, in a typical insect, is usually divided into regions known as the mouth, pharynx (which includes our buccal cavity), oesophagus, crop (ingluvies), and proventriculus (gizzard). The hind-gut, where more highly developed than in Anopheles, has been divided into ileum (short intestine), long intestine, colon, and rectum.

Dimmock styles our buccal cavity ‘pharynx,’ and includes our pharynx with the oesophagus. Annett and Dutton describe our buccal cavity as the ‘ascending portion of the pharynx.’ The structure of the parts we have described separately as buccal cavity, pharynx, and oesophagus, with their sharp limitations, lend themselves best we think to the divisions we have given, our terminology having the advantage of terseness.

^{page 170 note 1} Packard (p. 303) states that Meinert (‘Trophi Dipterorum’) described the pharynx as the principal, and in most Diptera as the only part of the pumping apparatus (antlia). Meinert appears to have recognised the nature of the mechanism. His figure of the pump, given by Packard (p. 78, figure 81) and the muscles attached thereto, the ‘musculis antliae,’ taken from Culex pipiens, is fairly accurate. A similar apparatus is also present in other flies, in Hemiptera and Lepidoptera. Dimmock (1881, p. 19) rightly states: ‘;This bulb is the chief sucking organ in the female Culex’ he is in error however when he states (p. 13) that it is absent in the male insect.

^{page 173 note 1} According to Packard (p. 305) this sac is always on the left side in Diptera. In our sections it appears median. It appears that such sacs are present in most Diptera and Lepidoptera, where they are falsely called a sucking stomach. In the Lepidoptera they generally contain only air. Newport found the sac filled with food in the flesh-fly and in Eristalis, the latter having fed on pollen. Graber also saw food enter the reservoir in flies, the food being coloured. In Hymenoptera the reservoir occurs as a pouch communicating with the oesophagus, and in the honey-bee it is to be distinguished from the ‘honey-sac,’ which is the crop or proventriculus. Nevertheless, in bees the reservoir has been seen to be filled with honey.

^{page 179 note 1} It is of interest to note that Schoo (1902, Feb.?) considers that it is chiefly serum which is ejected. He weighed A. maculipennis before (weight 1.9–4.2 mg., average 3 mg.) and after feeding (weight 3.6 to 6.4 mg.), concluding that the amount of blood ingested weighed 1.4 to 2.9 mg.

^{page 180 note 1} According to Packard (p. 324) Dragon-flies, Orthoptera and Lepidoptera swallow some air with their food.

^{page 180 note 2} Weissmann (1864, cited by Packard, p. 311) already regarded the proventriculus of flies as an intussusception of the oesophagus.

^{page 183 note 1} This requires further study. Packard (p. 316) states of some insects that the inner (circular) layer of muscles is unstriated, the outer (longitudinal) striated. On p. 324 occurs the remarkable statement: ‘Suctorial insects draw in their liquid food by the contractions followed by the dilatations of the mid-intestine,’ a conception which is obviously false.

^{page 185 note 1} Giles (2nd ed. 1902, p. 103) is evidently in error when he states that there are four anal papillae. He states that they are connected by short ducts to the intestine, and that they probably secrete some ‘fluid accessory to digestion.’

^{page 186 note 1} Giles (2nd ed. 1902. p. 100), speaks of the salivary duct as ‘ chitinous tube prolonged from the lining of the buccal cavity,’ this being incorrect.

^{page 189 note 1} See Plate VI. This is not shown in the diagrammatic cross-sections of the head in Plate VII, Figs. 1–3, nor in Fig. 4.