MOLLUSCA. 
249 
nor tliose published without any description, and intelligible from 
the quotation of a figure only (like those of Bolten), can have 
any claim to priority. 
The fancy of changing well-known and generally adopted 
specific names for others of sometimes a very dubious character 
is also not yet extinct. M. Bourguignat, in the papers quoted 
above, substitutes the almost unutterable name of Helix iso- 
gnomostoma for the w^ell-known Helix personata (Lam.), and 
Anodonta arenaria for A. cellensis : the first, because Gmeliii 
confounded the German species with the American one under 
this name ; and the second, because Sehroter w as unable to dis- 
tinguish an Anodonta from Mya arenaria^ L. ! 
The vague distinction made by some authors between genera 
and svhgenera has been represented as another cause of the 
unsettled state of our nomenclature.'’^ It is, without doubt, 
a sign of progress in our science to distribute numerous species 
of a genus in subdivisions called sections, groups, or subgenera 
by the different authors. Perhaps they might have been best 
designated by adjectival names derived, when possible, from the 
name of the typical species, like those used by palaeontologists 
for the groups of Ammonites, Terebratulse, &c. Ihus, M. Crosse 
names a distinct subdivision of Bulimus ‘^les Bulimes auriculi- 
formes.^^ But zoologists, after the example first given by Cuvier, 
generally give su!)stantive names to these subgenera, which 
certainly has the advantage tliat no further change is necessary, 
if, as is frequently the case, the subgenus established by one 
author is regarded as a genus by another ; but this practice has 
the disadvantage of leading to a rather rash and inconsiderate 
creation of new names : if the genus should not prove to be 
valid, it may be taken as a subgenus. In Morch^s revolutionary 
rather than reformatory lists of shells, it is quite impossible to 
find out wdiich names are intended for genera and which for 
subgenera. Messrs. Adams now frequently use a name as a 
generic name which w^as proposed in their great work on the 
Genera of Mollusca as subgeneric only. Mr. Carpenter himself 
uses names of his new subgenera^^ just as if they were generic. 
The late Dr. Albers and the Recorder have several times been 
severely blamed, especially in this year by M. Crosse in his 
excellent memoir on the Bulimes auriculiformes,^^ for having 
introduced new genera which, in reality, were understood and 
represented by us «as subgenera only, as may be easily seen from 
the manner in w hich the species are enumerated. 
Finally, also the distinction between species and varieties has 
been a matter of question this year. Mr. Carpenter ventured 
to describe some shells as new, acknowledging by the form of 
the name itself that he is quite undecided (or rather indifferent) 
whether they should be regarded as good species or as new 
varieties of species known (Ann. &Mag. Nat. Hist. xiii. pp. 311- 
