272 Proposed Reform of Zoological Nomenclature. 
Mexican species termed (through erroneous information of its 
habitat) Picus cafer, or an olive-coloured one Muscicapa atra, or 
when a name is derived from an accidental monstrosity, as in Picus 
semirostris of Linnzus, and Helix disjuncta of Turton, we feel 
justified in cancelling these names, and adopting that synonym 
which stands next in point of date. At the same time we think 
it right to remark, that this privilege is very liable to abuse, and 
ought therefore to be applied only to extreme cases and with great 
caution. With these limitations we may concede that 
§ 11. A name may be changed when it implies a false 
proposition which is likely to propagate important errors. 
[Names not clearly defined may be changed.] 
Unless a species or group is intelligibly defined when the name 
is given, it cannot be recognised by others, and the signification of 
the name is consequently lost. Two things are necessary before 
a zoological term can acquire any authority, viz., dejinition and 
publication. Definition properly implies a distinct exposition of 
essential characters, and in all cases we conceive this to be indis- 
pensable, although some authors maintain that a mere enumera- 
tion of the component species, or even of a single type, is sufficient 
to authenticate a genus. To constitute publication, nothing short 
of the insertion of the above particulars in a printed book can be 
held sufficient. Many birds, for instance, in the Paris and other 
continental museums, shells in the British Museum (in Dr Leach’s 
time), and fossils in the Scarborough and other public collections, 
have received MS. names which will be of no authority until they 
are published.* Nor can any unpublished descriptions, however 
exact (such as those of Forster, which are still shut up in a MS. © 
at Berlin), claim any right of priority till published, and then only 
from the date of their publication. The same rule applies to 
cases where groups or species are published, but not defined, as in 
some museum catalogues, and in Lesson’s “ Traité d’Ornitho- 
logie,” where many species are enumerated by name, without any 
description or reference by which they can be identified, There- 
fore,— 
§ 12. A name which has never been clearly defined in 
some published work should be changed for the earliest 
name by which the object shall have been so defined. 
[Specific names, when adopted as generic, must be changed.] 
The necessity for the following rule will be best illustrated by 
* These MS. names are in all cases liable to create confusion, and it is 
therefore much to be desired that the practice of using them should be avoided 
in future. 
