194 Mr. Cosmo Melvill on the 



chain of connection is thereby shown. I propose to call this 

 C. amphithales^ and am convinced it is specifically distinct, 

 having seen several specimens, all alike, though mostly a 

 little worn on the dorsal surface, which is, however, always 

 smooth^ specimens in fine condition having been lately sent 

 home by Mr. Bairstow. As will be seen subsequently, I 

 append to this paper a list of all the known kinds, with 

 their synonyms and varieties, devised upon a circular system ; 

 that is to say, although the species are necessarily arranged 

 in what appears at first sight a tabular form — from Nos. i 

 to 189 — I mean that No. 189 will bear the nearest link to 

 188 on one hand and to No. i on the other, and so on. 

 The extremes that according to this circular catalogue are 

 thus placed in juxtaposition, C. leucodon (Brod.) and C. 

 Valentia (Perry), or princeps (Gray) are, to quote a very 

 interesting writer,* " probably the tips of the branches of the 

 Conchological staiiimbaimi or genealogical tree, which may 

 have reached the limit of possible development in their own 

 direction." Both of these will be discussed more fully in 

 another paragraph, it will suffice to say at present that 

 there would seem to be some divided marks of affinity 

 to bind them to each other, isolated as they stand in 

 the series. 



Again, the Trivice, hitherto usually considered a distinct 

 genus, are intimately connected with the Cyprcea proper on 

 the one hand through T. pustulata (Lamk.), the young of 

 which Infringes closely upon Cyprceovida Adamsonii (Gray), 

 and, on the other, through the numerous smooth varieties of 

 Trivia stapJiylcca (L.), which trench upon C. Helvola (L.), 

 var. Haivaiiensis, and the rest of the members of that section 

 {Erosce) whose marginal pitting of the sides is also found 

 in the varieties of siaphylcea just mentioned, e.g. polita 

 (Roberts), limacina (Lamk.), etc. 



' Notes by a Field Naturalist in the Western Tro])ics, by the Rev. H. H. 

 Iliggins, M.A., 1877. 



