242 Mr. E. Billings on the Genus Athyris. 
substituted Merista and Athyris, at the same time transferring 
the latter to Spirigera, as in the extract given in the note below 
(op. cit. p. 101). 
Upon a careful examination of all the circumstances, I think 
it will be found that, according to the laws of nomenclature, 
this change cannot be sustained. I shall therefore quote some 
of those laws, and endeavour to apply them to this case. 
The first rule reads thus :— 
“*§ 1.—The name originally given by the founder of a group or 
the describer of a species should be permanently retained, to the 
exclusion of all subsequent synonyms.” 
It seems scarcely necessary to quote such a rule as this. I 
only do so in order to make the comment that it is the most 
important of all the laws of nomenclature, and that its opera- 
tion cannot be prevented in any case by merely technical objec- 
tions or by any error in the details of a generic or specific de- 
scription. Provided the original diagnosis contains sufficient in 
substance to enable the scientific public to identify the group, 
trivial errors, from which the writings of no naturalist are free, 
will not have any effect. All that can be done is to rectify, 
not to destroy. One of the exceptions to this rule is thus ex- 
pressed in No. 1] :—* A name may be changed when it implies 
a false proposition which is likely to propagate important errors.” 
According to this exception, if the name Athyris should be 
applied to the S. concentrica group, there is a possibility of its 
falling into the list of synonyms; for, although no very impor- 
tant error would be superinduced, yet few naturalists can apply 
it to shells with a well-defined foramen without feeling that such 
an application is to some extent inconsistent with the purity of 
scientific nomenclature. 
*“§ 3.—A generic name, when once established, should never be 
cancelled in any subsequent subdivision of the group, but retained 
in a restricted sense for one of the constituent portions. 
“$4. A generic name should always be retained for that portion 
of the original genus which was considered typical by the.author.” 
This latter rule is preceded by some introductory observa- 
tions which should be embodied in it, as they, in fact, form a 
1854) qu’il avait, en 1851, proposé le nom de Merista (Jahrb. k. k. geol. 
Reichsanstalt, ii. tv. 150, 1851. Mentionné encore dans Leonhard’s Neues 
Jahrbuch, p. 127, 1854) pour le groupe renfermant ces derniéres. J’aban- 
donne donc la proposition que j’avais faite en 1853, et je conserve indif- 
féremment |’ Athyris, M‘Coy, ou le Spirigera, d’Orb., pour le T. concen- 
trica; et Merista, Suess, pour les T. tumida, Herculea, ete.” 
