Besides, it has been clearly established, that one at least of the gasteropoda is furnished with the power of producing sounds. Dr. Grant, in 1826, communicated to the Edinburgh Philosophical Society the fact, that on placing some specimens of the _Tritonia arborescens_ in a glass vessel filled with sea water, his attention was attracted by a noise which he ascertained to proceed from these mollusca. It resembled the "clink" of a steel wire on the side of the jar, one stroke only being given at a time, and repeated at short intervals.[1] [Footnote 1: _Edinburgh Philosophical Journ_., vol. xiv. p. 188. See also the Appendix to this chapter.] The affinity of structure between the _Tritonia_ and the mollusca inhabiting the shells brought to me at Batticaloa, might justify the belief of the natives of Ceylon, that the latter are the authors of the sounds I heard; and the description of those emitted by the former as given by Dr. Grant, so nearly resemble them, that I have always regretted my inability, on the occasion of my visits to Batticaloa, to investigate the subject more narrowly. At subsequent periods I have since renewed my efforts, but without success, to obtain specimens or observations of the habits of the living mollusca. The only species afterwards sent to me were _Cerithia_; but no vigilance sufficed to catch the desired sounds, and I still hesitate to accept the dictum of the fishermen, as the same mollusc abounds in all the other brackish estuaries on the coast; and it would be singular, if true, that the phenomenon of its uttering a musical note should be confined to a single spot in the lagoon of Batticaloa.[1] [Footnote 1: The letter which I received from Dr. Grant on this subject, I have placed in a note to the present chapter, in the hope that it may stimulate some other inquirer in Ceylon to prosecute the investigation which I was unable to carry out successfully.] Although naturalists have long been familiar with the marine testacea of Ceylon, no successful attempt has yet been made to form a classified catalogue of the species; and I am indebted to the eminent conchologist, Mr. Sylvanus Hanley, for the list which accompanies this notice. In drawing it up, Mr. Hanley observes that he found it a task of more difficulty than would at first be surmised, owing to the almost total absence of reliable data from which to construct it. Three sources were available: collections formed by resident naturalists, the contents of the well-known satin-wood boxes prepared at Trincomalie, and the laborious elimination of locality from the habitats ascribed to all the known species in the multitude of works on conchology in general.