File:EB1911 Hexapoda - embryo of Gryllotalpa.jpg

English: Morphology of an Insect: the embryo of Gryllotalpa, somewhat diagrammatic. The longitudinal segmented band along the middle line represents the early segmentation of the nervous system and the subsequent median field of each sternite; the lateral transverse unshaded bands are the lateral fields of each segment; the shaded areas indicate the more internally placed mesoderm layer. The segments are numbered 1-21; 1-6 will form the head, 7-9 the thorax, 10-21 the abdomen. A, anus; Abx₁ Abx₁₁, appendage of 1st and of 11th abdominal segments;Ans, anal piece = telson or 12th abdominal segment; Ant, antenna; De, deuterencephalon; Md, mandible; Mx₁, first maxilla; Mx₂, second maxilla or labium; O, mouth; Obcl, rudimentary labrum and clypeus; Pre, protencephalon; St₁ St₁₀, stigmata 1 and 10; Terg, tergite; Thx₁, appendage of first thoracic segment; Tre, tritencephalon; Ul, a thickening at hinder margin of the mouth.