Ikl 



PART IV 



RACHIGLOSSA 



This fourth part of the Gastropoda of the Siboga Expedition, deals with the large section 

 of the rachiglossate moUusks; it contains the enumeration of a much larger number of species 

 than its predecessor, no less than 335 species having been recorded, of which I describe 45 

 as new to science, which are all figured ; moreover a few new varieties of these and longer 

 known species are described and many of them are also figured. I hope not to have exaggerated 

 the number of novelties, but may observe that I nearly never described a new form unless it 

 has been compared by Mr. E. A. Smith, I.S.O., of the British Museum, in order to avoid 

 redescribing forms already known, especially with a view on the numerous unfigured ones of 

 Adams. I here openly bring him my kind thanks for his never failing readiness in this respect. 

 I have scarcely less to thank, Mr. J. Cosmo Melvill', M.A., D.Sc. for much information in 

 the same line and for the loan and even donation of specimens. Dr. Sturany, as acknowledged 

 in due place in this work, sent me for comparison his new species of Nassa of thie group of 

 N. munda etc. and in some other cases I received assistance from several persons in naming 

 specimens and beg them all to accept my kind thanks. As to litterature, I continually could 

 make use of the rich library of Teyler's Museum and I am infinitely grateful to its most obliging 

 librarian ]\Ir. Verwijnen. 



As to the location of species in the sections of genera I am not quite certain I have 

 always been right. In several cases I was able to ascertain their systematic position by examining 

 the radulae, but in many other cases when the soft parts were wanting, I must make the words 

 of Tryon (Manual of Conchology i^' series. Vol. II, p. 116) my own, when dealing with Ocinebra 

 he says: "with regard to these I claim the indulgence of brother conchologists, who may have 

 similarly found themselves in the predicament of being compelled to place something somewhere, 

 just to get it off their hands". The sections of Mitridae, Nassa, Columbella and other genera 

 are not always limited clear enough, to avoid mistakes in this respect. 



I have on this occasion to repair a mistake in the first part of my work. In erecting 

 the family Neritilidae, I came to the conclusion of its difference, after the manuscript was ready, 



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SIBOGA-EXVEDITIE XI,IX'(/. 33 



