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Show 1895.] MOLLUSCA O F T H E A N D A M A N A N D NICOBAR ISLANDS. 439 fatigable collector, and he added many new species to the list. As Morch states quite truly, Copenhagen was, one may say, at this time the capital of the science of couchology, it being sufficient to mention the names of Miiller, Chemnitz, Spengler, Fabricius, and Begenfuss. With this previous work and material I am enabled to give a very full list of what has been obtained there ; it does not profess to be exhaustive, as I am aware that collections are constantly arriving in this country, but I trust the list will be useful for others to add to. For instance, I know of no Laud-Shells having been found on either of the small volcanic islands, and it would be of great interest if any should occur, having reference to the means whereby such forms can be transported. The difficulty of landing on many of these rocky islets, and of getting back to the ship, is so great that very few opportunities occur, and then the time on shore is very limited, so that a good deal has yet to be done. It is remarkable how very few species range beyond the islands on which they have been found; thus there are only 8 species common to the Andamans and Nicobars, while only 7 range on the south to Sumatra and Java, and only 5 north to Burmah. However, there is a distinct and close relationship in the past shown with Burmah and Arakan by so many closely allied species, and equally marked is tbe paucity of forms having an alliance with those of Peninsular India. Marked diversity of form and restricted ranee is displayed among the Operculates, in Cyclophorus especially, by tbe turbinate shells of C. leai, C. foliaceus, &c, while Alyceeus and Diplommatina are very limited in species. No species of Glausilia has yet been recorded from the Andamans, and only three from the Nicobars, and tbey are very close allies. The genus Microcystina is represented by several species; although M. cryptomphala from Lower Bengal was placed in it by me, yet, as its anatomy is not known, this extension of the range is not certain. Five species occur in Borneo, but the animal has yet to be examined. The genus Plectopylis, so common in Burmah and N.E. India, is absent. It is interesting to note the occurrence of Omphalo-tropis, a genus represented by numerous species in the Mauritius, and here represented by 7 species ; but it does not occur in India or on the mainland beyond the Andaman Sea. Hyalimax is another genus with a similar range. The physical features of tbis group of islands have been treated of by many authors, and their position, as regards the whole volcanic line of action, is now defined as one lying outside and to the west of it, and having its extension to the south-eastward in the Nias Islands off Sumatra. Blanford and Medlicott, in the ' Manual of Geology of India,' vol. ii. p. 732, may be consulted; an interesting account by Mr. A. 0. H u m e and the other members of an expedition to the islands is given in ' Stray Feathers,' vol. ii. (1874). Still later Dr. Prain, in the ' Proceedings of the Asiatic Society of Bengal,' April 1892, |