2. Eggs of Benhamina obliquata, Pleurobranchaea novaezelandiae, Archidoris wellingtonensis, Ctenodoris flabellifera, Aphelodoris luctuosa, Dendrodoris citrina and Siphonaria zelandica are deposited in gelatinous ribbons attached to rocks or sessile organisms. These species include the nudibranchs and limpet-like pulmonate in the series studied. Eggs of Zeacumantus subcarinatus are embedded in clumps of gelatinous matrix, not drawn out into a ribbon.

3. Eggs of Cabestana, spengleri, Argobuccinum tumidum, Cominella maculosa, C. glandiformis, Zeatrophon ambiguus, Neothais scalaris, Lepsia haustrum, Lepsiella scobina, Lepsithais lacunosa and Alcithoe arabica are deposited in capsules attached to rocks or sessile organisms. The capsules of Lepsia haustrum, Lepsiella scobina, Lepsithais lacunosa and Alcithoe arabica, which are carnivorous gastropods, are deposited on a basal membrane, which in the case of Cabestana spengleri extends upwards to form an open globose cup or basket containing the capsules.

4. Alcithoe arabica forms relatively enormous but correspondingly few capsules, attached singly (rarely in twos) to the bottom debris, with the reduction in the number of contained eggs to two, rarely three per capsule; the larvae are active and relatively large benthic animals when liberated.

5. No surface-floating molluscan eggs were recognised, for those of the first group above would appear but transiently if at all in the plankton; presumably the larvae of the second and third groups would appear in the neritic plankton, except that Alcithoe arabica has no planktonic stages, and apart from minor agencies such as the occasional deposition of a capsule on a gastropod shell tenanted by a Pagurid, is dependent on its own motility for dispersal.

6. A slight upward movement prior to oviposition occurs in the case of Cominella maculosa, whose forsaking of the normal muddy habitat in favour of rocks is presumably a prophylactic recourse against smothering of the eggs by silt. Also the nudibranchs usually spawn on weed or vertical rocky channels, possibly to escape silt and sand or benthic enemies, or to ensure optimum supplies of oxygen. But Alcithoe arabica spawns on debris on the sandy bottom of its normal habitat.

7. Apart from these slight upward movements, no spawning migrations have been detected, but Haliotis iris has a non-reproductive winter migration into deeper water. As shown by marked shells, this species and Amaurochiton glaucus have a “homing” tendency in that they return accurately to the same spot after a night foraging expedition, and in neither can this be interpreted, as has been claimed in the case of limpets, as a return to a spot where the irregularities of the rock surface are accurately matched by those of the shell margin. In the case of Lepsithais lacunosa, Archidoris wellingtonensis, and Ctenodoris flabellifera copulation is reciprocal; among the nudibranchs in general, copulation is a protracted process which occupies several hours.

8. In order to study further such phenomena as the transient appearance of opercula and shells in embryonic nudibranchs, the absorption of the nutritive material of the majority of encapsulated