Subgenus 1. Amphicraspedon, Haeckel.
Definition.—Both arms of equal size and form, without terminal spines of the branches.
1. Amphicraspedum maclaganium, n. sp. (Pl. 45, fig. 11).
Both arms equal, in the proximal half simple, in the distal half forked, with six to seven transverse septa; distal end of each branch rounded, blunt, somewhat broader than the base of the whole arm. Divergent axes of both branches concavely curved. Patagium incomplete, with elliptical perimeter, enveloping only the middle part of the shell. I call this interesting species in honour of Miss Nellie Maclagan, the learned translator of several zoological papers from German into English.
Dimensions.—Radius of each arm 0.25, basal breadth 0.07; distal breadth of each branch 0.08; equatorial breadth of the patagium 0.25.
Habitat.—North Atlantic, off Halifax, Station 50, surface.
Subgenus 2. Amphicraspedina, Haeckel.
Definition.—Both arms of different size or form, without terminal spines on the branches.
2. Amphicraspedum wyvilleanum, n. sp. (Pl. 45, fig. 12).
Both arms different. Larger arm simple, egg-shaped, with eleven convex joints, one and a half times as long as broad; smaller arm in the basal half simple, triangular, with six cap-like joints, in the distal half forked; both branches egg-shaped, with five joints and blunt ends. Patagium nearly complete with four to five concave chamber-rows. Called in honour of Sir C. Wyville Thomson.
Dimensions.—Radius of the larger simple arm 0.18, breadth 0.08; radius of the smaller forked arm 0.16; breadth of the branches 0.05; transverse breadth of the patagium 0.2.
Habitat.—South Atlantic, Station 333, surface.
Subgenus 3. Amphicraspedula, Haeckel.
Definition.—Both arms of different size or form, with terminal spines of the branches.
3. Amphicraspedum murrayanum, n. sp. (Pl. 44, fig. 10).
Both arms different in size; the larger one and a half times as long and broad as the smaller. Both arms triangular, forked at the broader distal end, with two very strong, conical, divergent,
