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6. An attempt to distribute the species of Olive (Oliva, 

 Lamarck) into natural groups, and to define some of 

 the Species. By Dr. J. E. Gray, F.R.S., V.P.Z. & Ent. 

 Soc, etc. 



Linnaeus divided the shell, usually called Olives by the dealers, 

 into three species, viz. Foluta porphyria, V. oliva, and V. ispidula. 



Gmelin added a few, and Lamarck, who published a monograph 

 of the genus in the 'Aunales du Museum,' extended the number to 

 sixty-two. Dillwyn reduced them back to eighteen. 



Duclos, who published the plates of a monograph of this genus in 

 1835, figures eighty-four recent species, and he considers twenty-two 

 of the species which Lamarck described as distinct, as only varie- 

 ties of other species. 



In 1850 Mr. L. Reeve, in the ' Conchologia Iconica,' published 

 the figures of 100 species, but without any attention to their affinity 

 to each other, and with scarcely sufficient care to the more important 

 part of the shell on which the separation of the species depends. 

 They are there inferior to those of M. Duclos. 



I believe that it is the uncertainty with regard to the number of 

 the species which has rendered these shells, which are certainly one 

 of the most beautiful in form, colour, and marking that we possess, 

 so little attended to by the general collector. This is the more re- 

 markable, as the shells are very extensively distributed over the 

 globe, and are easily collected, and therefore are easily procured by 

 the conchologist at a moderate rate ; though it is very difficult to 

 define the limits of many of the species on account of the great varia- 

 tion in the colour, and the extraordinary manner in which the mark- 

 ing gradually changes in their character ; while other species are 

 easily distinguished. 



All the species are easily separated into very distinct groups, de- 

 fined by variations in the form and structure of the shell, which are 

 evidently produced by important modifications in the structure of 

 the animal ; and to point out these groups is the object of this paper, 

 for I believe that by dividing the species or varieties, which have 

 been considered as species, into such groups, I shall do much to dis- 

 entangle the subject, and at least confine the confusion to definite 

 limits ; for if the groups are properly defined, it is only the specimens 

 belonging to one of these groups that can be varieties of each other. 



M. Duclos, in the monograph, divides the species into four 

 groups: — 1. Ancilloides (twenty-nine species) ; 2. Cylindroides (fifty 

 species); 3. Glandiformes (seventeen species) ; 4. Volutelles (seven- 

 teen species) . 



M. D'Orbigny, in his ' Voyage to South America,' formed M. 

 Duclos' s four sections into three genera, giving to the first section 

 the name of Olivina, to the second and third section that of Oliva, 

 and to the fourth Olivancillaria, apparently founded on the form 

 of the animal ; but it is only necessary to compare his figures of the 

 animal of the two species of the latter genus to show how little he 

 attended to his own characters. 



