ON ZOOLOGICAL NOMENCLATURE. 
39 
When a usage is established for an old name in some other way it is 
better to follow it, as L. for Linnaeus; St. Hil. for Saint Hilaire. (DC.) 
This rule has been followed by Lintiams, De Candolle, and all botanists up to a re- 
cent date. No particular rule has been laid down for the guidance of zoologists, but 
this will doubtless recommend itself to them when considered. In some later works, 
only those familiar with the literature can divine whether Bth. is the equivalent of 
Bentham, Beuth or Booth, Sz. of Schultz, Steetz or Szowitz; or what is the equivalent 
of Htsch., Hk., H.Bn., Bn. } Bit., Lrn., Reich, or Spng. 
Of Names to be preserved in writing, Dividing or Modifying 
the Limits of Existing Groups. 
§ L. A change in the diagnostic characters, or a revision which carries 
with it the exclusion of certain elements of a group, or the inclusion of 
new elements, does not authorize the change of the name or names of a 
group. 
§ LT. When a group or genus is divided into two or more groups, the 
original name must be preserved and given to one of the principal divis- 
ions. The division including the typical species of the primitive genus, 
if any type had been specified, or the oldest, best known or most character- 
istic of the species originally included when the primitive genus was first 
described by its author, is the portion for which the original name is to 
be preserved. If there is no section specially so distinguished, that which 
retains the larger number of species should retain the old name (DC.), 
but the latter cannot be applied to a restricted group containing none of 
the species referred to the primitive group by its author at the time when 
it was described or when he enumerated the species contained in it. 
The majority of the replies to query XII of the circular concur in the above. 
According to Linnaeus the name should remain with the most common and officinal 
species; an equivocal expression if there is one which is most common and another 
the officinal species. The Convolvulus sepium and the Erica vulgaris were very com- 
mon and very anciently named species when Brown made of one the genus Calystegia, 
and De Candolle of the other, his genus Calluna. It was, however, much better to do 
this than to change the names of a hundred species of Convolvulus, and two hundred 
of Erica. When there is no authoritative type, the number of species should always 
be taken into consideration. (DC.) 
§ LII. When an author has specified no type, it is then necessary, in 
dividing his genus, to retain his name for the subdivision containing the 
species, which the next subsequent author, treating of the genus has. 
specified or regarded as the typical exemplar. B. A. If no subsequent 
author has selected a type, the first species of the primitive author may 
frequently be taken as the type, or a species may be selected from among 
those originally specified as belonging to the genus when it was formed, 
due regard being paid to the necessity of retaining as many of the orig- 
inal species as possible in the division which is to retain the old name. 
It would, manifestly, be liable to introduce errors and confusion, if it were insisted 
that the first species should invariably be taken as the type, or were it permitted to 
