SUMMARY. 93 
a hump-backed or club-footed man into a distinct species from his 
uninjured brothers as putting such shells as these forward as distinct 
species. The innumerable divergences, not only in the direction 
of named shells, but into others not hitherto named, were so 
constantly springing up, that the direct lines appeared to constitute 
only a portion of the total lines of divergence. It must also be 
borne in mind that the varieties can only extend to the centre 
between two supposed species. 
Several of the shells appearing in the early part of this paper 
are treated as if they were distinct, whereas in the latter pages they 
are placed as varieties of other shells ; this arises from the fact that 
the numerous comparisons which had to be made, and the extra- 
ordinary number of examples which had to be compared, produced 
at length sufficient evidence to induce me to unite these shells 
under the head of varieties. 
For the last fifteen or sixteen years I have been examining 
the subject of variation, and in all the genera containing an ex- 
tensive series of what are termed species the study has presented 
results very similar to those obtained from the shells in the genus Nassa. 
The largest collection of Olives known is contained in eighteen well 
filled drawers in the cases of the Free Public Museum of Liverpool, 
and I firmly believe, that if carefully examined, the two hundred and 
twenty species would be reduced to a dozen, or at the most, twenty. 
The greater part of the species named and described by myself 
would be reduced to the rank of varieties. An examination of 
the Cowries would result in a general amalgamation of whole lines of 
variable shells, most of which have been described as species for the 
money-value attached to a name. Let any person examine the 
Cyprzea onyx, Linn., and compare with it such shells as C. spadicea, 
Swain., C. pyrum, Gmel., C. physis, Brocchi, &e. These two last- 
named shells are closely allied to varieties of C. carnicolor, an 
acknowledged variety of C. onyx. The C. eburnea, Barnes, 
C, miliaris, Gmel., and C. Lamarckii, Gray, are the same shell, the one 
an albino and the other two differently marked varieties, the 
C. turdus, Lam., might follow as a somewhat flattened variety. The 
offshoots of C. cribraria, Linn., should never have been separated 
