Chætognatha, pp. [366‑369]. Myzostomea, pp. [369], 370. Gastrotricha, p. [370].

Chapter XVI.

Nematelminthes, pp. [370‑379]. Acanthocephala, pp. [379‑381].

Chapter XVII. Tracheata.

Prototracheata, pp. [382‑387]. Myriapoda, pp. [387‑395]. Insecta, pp. [395‑429]. Embryonic membranes and the formation of the layers, pp. [400‑406]. Formation of the organs, pp. [406‑417]. Special types of larvæ, pp. [417‑419]. Metamorphosis and heterogamy, pp. [420‑429]. Arachnida, pp. [431‑455]. Formation of the layers and general development, pp. [431‑446]. Formation of the organs, pp. [446‑455]. Formation of the layers and embryonic envelopes in the Tracheata, pp. [456‑458].

Chapter XVIII. Crustacea.

History of larval forms, pp. [459‑511]. Branchiopoda, pp. [459‑465]. Malacostraca, pp. [465‑487]. Copepoda, pp. [487‑492]. Cirripedia, pp. [492‑500]. Ostracoda, pp. [500‑502]. Phylogeny of the Crustacea, pp. [502‑511]. The formation of the germinal layers, pp. [511‑521]. Comparative development of organs, pp. [521‑529].

Chapter XIX.

Pœcilopoda, pp. [534‑538]. Pycnogonida, pp. [538], 539. Pentastomida, pp. [539‑541]. Tardigrada, p. [541]. Summary of Arthropodan Development, pp. [541‑543].

Chapter XX. Echinodermata.