25 
The same rule obtains when two or more species or subspecies are 
united to form a single species or subspecies. 
Recommendation. — In absence of any previous revision, the establishment of 
precedence by the following method is recommended : 
(a) A generic name accompanied by specification of a type has precedence over 
a name without such specification. If all or none of the genera have types speci- 
fied, that generic name takes precedence the diagnosis of which is most pertinent.. 
( b ) A specific name accompanied by both description and figure stands in pref- 
erence to one accompanied only by a diagnosis or only by a figure. 
(c) Other things being equal, that name is to be preferred w r hich stands first in 
the publication (page precedence). 
Discussion.— T he genus Taenia, 1758, as at present constituted, is 
composed of a union of the genera Taenia , 1758, Hydatigena , 1782, 
Megocephalos , 1782, Vesicaria , 1788, Hydatula , 1790, Alyselminthus , 
1800, dialysis , 1803, Physcliiosoma , 1809, Hydatigera , 1816, Trachelo- 
campylus , 1847, Arynchotaenia , 1850, Acanthotrias , 1858, Taeniarhyn- 
chus , 1858, Cystotaenia , 1863, and JTeotenia , 1886; opinion might differ 
in regard to which name should be used, bat by the law of priority 
and by article 28 Taenia is the correct name for the genus which con- 
tains T. solium. 
The species Taenia saginata , 1782, as at present constituted, is com- 
posed of several forms which were originally described as distinct. 
Hymenolepis , 1858, is composed of a union of Hymenolepis , 1858, 
Tiplacanthus , 1858, Lepidotrias , 1858, and Trepan idotaenia, 1892. 
Art. 29. If a genus is divided into two or more restricted genera, 
its valid name must be retained for one of the restricted genera. 
If a type was originally established for said genus, the generic name 
is retained for the restricted genus containing said type. 
Discussion. — A division of a given genus into more restricted genera 
is a natural result of our advance in anatomical knowledge. Linnaeus 
in 1758 included in Taenia species which are now classified in three 
more restricted genera. Instead of proposing three new names for 
these more restricted groups the original name is retained for one of 
them, namely, for the group which contains the type (I solium ). 
Fasciola , 1758, is now divided into a large number of genera, but the 
fact that Fasciola as used to-day is not so broad a genus as when used 
by Linnaeus does not constitute sufficient ground for rejecting this 
name. 
The problem presented is almost the same as that of typhoid fever 
in 1860, when Zenker recognized that a distinct clinical entit}^ (trichi- 
nosis) had been included in t} T phoid. The newly recognized disease is 
now called trichinosis, but t}’phoid is still used for a part of the old 
composite malady. 
If a genus has no type species, and if the genus is divided, it not 
infrequently occurs that different authors apply the original generic 
name to different subdivisions of the original genus, and confusion in 
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