98 Zoological Nomenclature. 
extensive. It thus becomes necessary to —— oe ae, 26 ~ x enn 
and to save their detaitons continually more 
this process, it is an act of justice to the original author ne his Pipl phate 
psa never be lost sight of; and it is no less essential to the welfare of the 
science, that all which is so und i in its nom segeiewens should remain unaltered 
amid the additions which are continually Sein g made to it. On this ground 
we recommend the adoption of the following rule :— 
§ 3. A generic name, when once established, should never 
be canceled in any subsequent subdivision of the group, but 
retained in a restricted sense for one of the constituent | por- 
tions. 
ana names to be retained for the typical portion of the o 
When a genus is subdivided 1 into other genera, the original name Pond be be 
retained for that portion of it which exhibits in the greatest degree its essen- 
e doing so. ny cases be cor- 
rectly inferred that the Jirst species mentioned on their fet if found ra 
rately to nly definition, was regarded by them as the ty 
specific name, or its synonyms, will also often serve to point out the pal 
saa whic by implication en be regarded as the — type of a ge- 
In in restoring the of the old genus 
re ite peat signification, even pole later Side pe done otherwise. 
We submit therefore that :— 
§ 4. The generic name should always be retained for that 
portion of the original genus which was considered typical by 
the author. 
Example.—The genus, Picumnus was ape age by ee and in- 
cluded two groups, one with four toes, the o nivel e, the former of 
which was regarded by the author as typical. vain si aan in raising 
these groups at a later period to the rank of genera, ate ea apd name, a 
the 
rect sense, canceling the name, u -, and imposin ga new name 
on the three-toed group which Swainson had si: led Picumnus 
* This course has been systematically followed by some writers, and when 
carelessly ‘fone has often led to unfortunate and absurd results, especially whep 
applied to the earlier writers, since it often happens t that the actual position of the 
st species, in the restricted m with certainty. 
Thus in the XIIth edition, Syt. Nat, Mactra ‘includes eight oo most of which 
are now referred to distinet genera, but the = name is variously restricted 
M. Sprengleri, as the type, and thus forms 
a oon ‘with but tage species, which had long Senne received another name, w. 
to the eo ie including the well known European species and proper type; 
M. of Lam. 1801) hn applies the name Trigonella DaCosta, but 
(as it wabe seem) being so: t doub as tothe real affinity of M. Spren- 
ts this s Trigonella ! us we have in the same catalogue 
one species of a, and that the first, appearing in two genera,—an 
instance m re d as dental error were it not that o 
of like character appear in the same and other lists, viz., Hemimactra Sayi, p. 33. 
) Sayi, on p. 45, being in this case placed 
ina autToreat= subfamily,” and Anatina Periph Lar, p. 51, appears again on 
the e page as a synonym of Periploma in valvis, with no explanation. 
(See ey ch <r og a vols. iii — iv, Appendix, ‘‘ Catalogue 
