With the two exceptions that we regard the Trilobites as more nearly allied to the Crustacea, and have therefore considered them apart, and have treated the Pycnogonida independently of the Arachnida, we have followed Lankester in his classification, though not always in his nomenclature:—
Sub-class 1. Delobranchiata[[205]] (Merostomata).
Order (i.) Xiphosura.
Order (ii.) Eurypterida (= Gigantostraca, Extinct).
Sub-class 2. Embolobranchiata.
Order (i.) Scorpionidea.
Order (ii.) Pedipalpi.
Order (iii.) Araneae.
Order (iv.) Palpigradi.
Order (v.) Solifugae.