The Rev. H. G. Barnacle describes the musical properties of _Achatinella_ in the following terms:[120] “When up the mountains of Oahu I heard the grandest but wildest music, as from hundreds of Aeolian harps, wafted to me on the breezes, and my companion (a native) told me it came from, as he called them, the singing shells. It was sublime. I could not believe it, but a tree close at hand proved it. On it were many of the _Achatinella_, the animals drawing after them their shells, which grated against the wood and so caused a sound; the multitude of sounds produced the fanciful music. On this one tree I took 70 shells of all varieties.” =Habits of the Agnatha.=--Not much is known of the habits and mode of life of the _Agnatha_, or carnivorous Land Mollusca. In this country we have only two, or at most three, of this group, belonging to the genus _Testacella_, and, in all probability, not indigenous to our shores. There seems little doubt, when all the circumstances of their discovery are taken into account, that both _Testacella haliotidea_ and _T. Maugei_ have been imported, perhaps from Spain or Portugal in the first instance, along with roots imbedded in foreign earth, for their earliest appearances can almost invariably be traced back to the neighbourhood of large nursery grounds, or else to gardens supplied directly from such establishments. The underground life of _Testacella_ makes observation of its habits difficult. It is believed to feed exclusively on earthworms, which it pursues in their burrows. Continued wet weather drives it to the surface, for though loving damp soil it is decidedly averse to too much moisture, and under such circumstances it has even been noticed[121] in considerable numbers crawling over a low wall. In the spring and autumn months, according to Lacaze-Duthiers,[122] it comes to the surface at night, hiding itself under stones and _débris_ during the day. Earthworms are, at these periods, nearer the surface, and the _Testacella_ has been seen creeping down into their burrows. The author has taken _T. Maugei_ abundantly under clumps of the common white pink in very wet weather, lying in a sort of open nest in the moist earth. On the other hand, when the earth is baked dry by continued drought, they either bury themselves deeper, sometimes at a depth of 3 feet, in the ground, or else become encysted in a capsule of hardened mucus to prevent evaporation from the skin. When first taken from the earth and placed in a box, the _Testacella_ invariably resents its capture by spitting up the contents of its stomach in the shape of long fragments of half-digested worms. [Illustration: FIG. 20.--_Testacella haliotidea_ Drap., protruding its pharynx (_ph_) and radula (_r_); _oe_, oesophagus; _p.o_, pulmonary orifice; _sh_, shell; _t_, tentacles (after Lacaze-Duthiers).]