. The atoll of Funafuti, Ellice group: its zoology, botany, ethnology, and general structure based on collections made by Mrs. Charles Hedley, of the Australian museum, Sydney, N. S. W. THE MOLLUSCA—HEDLBY. 427 Beneath the head is a flap terminating anteriorly in two pro- cesses and arising from a deep cleft between the mouth and the operculum. Treating of the same or an allied species from Guam, Quoy and Gaimard* describe this as an anti-buccal appendage and figure it from above. I regard it as the relic of a degenerated propodium. The accompanying sketch (Fig. 17) in profile, of an animal ha
. The atoll of Funafuti, Ellice group: its zoology, botany, ethnology, and general structure based on collections made by Mrs. Charles Hedley, of the Australian museum, Sydney, N. S. W. THE MOLLUSCA—HEDLBY. 427 Beneath the head is a flap terminating anteriorly in two pro- cesses and arising from a deep cleft between the mouth and the operculum. Treating of the same or an allied species from Guam, Quoy and Gaimard* describe this as an anti-buccal appendage and figure it from above. I regard it as the relic of a degenerated propodium. The accompanying sketch (Fig. 17) in profile, of an animal half drawn out of the shell and stript of the operculum, will better convey an idea of this organ than figures taken from Fig. 17. When a o-asteropod retreats into the shell it doubles the foot either lengthwise, as in some inoperculate forms, or across, as in most oper- culates. In the latter case when completely retracted, the foot is so folded head to tail that the anterior half of the sole is applied to the posterior; the operculum then closes the aperture. In a sedentary form this position of retraction might become permanent. Where the foot never serves for progression, but continues to maintain a useful operculum, it is easy to imagine that the fore part of the folded foot would become atrophied and that as it diminished the hind part would enlarge. This is the history suggested for the shrunken propodium of Vermetus, which lies tucked away between the mouth and the operculum. The process of evolution perhaps continued in the direction of utilising the appendices of the pro- podium as tentacles. This species was collected by Hugh Cuming at Marutea, Pau- motus, and opercula of it were received from Lifu by Melvill and Standen. In a preceding article (p. 243) I have quoted a descrip- tion of a mollusc from Mangaiia, called " ungakoa," which is probably this. In Java it is known as "karang," which Morch translates as "coral ; The o
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