Summary.1 Cleavage, at first total, commences before the accumulation of the yolk, and later becomes superficial.2 A blastoderm covering the yolk is formed.3 A germinal band is formed by further division of the blastoderm cells along the ventral surface of the embryo.4 The band terminates anteriorly in a large cap of cells, posteriorly in a similar but smaller cap of cells.5 The anterior cap differentiates into:‐ (a) the central nervous system; (b) the segmental appendages; (c) the anterior plaque of endoderm.6 The whole development proceeds singularly directly to the definitive form of the larva.7 Coelomic vesicles have not been traced at any stage.8 The genital rudiments differentiate from the inner part of the germinal band posterior to the third pair of walking legs and are solid structures.9 The posterior polar cap proliferates a mass of cells which indents the yolk at its posterior end and is therefore responsible for the morphological aspects of the lateral caeca.10 The posterior mass of cells differentiates dorsally into the mid‐gut, or colon, and ventrally into the upper rectum or post‐colon. The malpighian tubules arise at the upper end of the post‐colon.11 The proctodœal invagination sinks into the posterior mass of cells and is the only part of the hind‐gut to be lined with chitin.12 The stomodœum arises between the cheliceral rudiments and does no