408 THE AMERICAN NATURALIST. [Vor. XXXV. 
because of their inadequacy and of the heterogeneous character of 
the genera so formed. Then even the groups which were best made 
were taken as subgenera rather than in their true place as genera, 
and even subfamilies, which Looss is unquestionably the first to 
recognize in any broad way. This view does not in the least under- 
estimate the admirable work of Braun and Lühe, which has appeared 
almost synchronously with that of Looss, and which, though dealing 
with fewer forms, furnishes evidence of the naturalness of the 
proposed dismemberment by the independent selection of identical 
groups. 
Looss discusses first the law of priority in relation to helmin- 
thology, and advocates on cogent grounds the dating of generic 
names in this field from Rudolphi, *the Linnzus of helminthology." 
Though much to be desired, his proposal must still be regarded as 
impracticable in view of the ciose relation of synonymy in all groups. 
Looss protests strongly, and, most will admit, rightly too, against the 
use of conjecture in restoring old generic names and cities from 
Rudolphi Hemiurus and Echinostoma as recognizable and evidently 
good genera, with Sphaerostoma as unrecognizable and Schisturus 
which depends upon pure conjecture. The law of priority is based 
upon the legal presumption that the literature is available everywhere, 
but a comparison of original specimens is not called for, since they 
exist, if at all, in a few places at most. The replacement of specific 
names, already well fixed, by comparison of the originals is hence in 
violence with the wording of the law ; if, however, it is to be carried 
out, general interests demand the earliest possible revision of all 
originals, since in this way the least disturbance will be produced. 
Names of species which do not exist in original specimens and which 
are not recognizable should be dropped at once so as not to burden 
the literature further. Looss then refers to the custom of Rudolphi 
in citing unknown parasites by the name of the host in genitive ; 
Eg., Distoma meropis, which should be interpreted as “a distome 
from Merops,” but which, as the author wrote in Latin, has the 
outward form of a generic and specific combination. Such names 
are pure nomina nuda, since a diagnosis is lacking and were so 
regarded by the author, since he never used a genitive as a specific 
name, and since he also never omitted the “R.” which is lacking 
after these, from the new species actually described. 
The second section of the paper on the taxonomy of the distomes 
opens with a discussion of previous efforts in this direction, an 
of the great disparity in form and structure between Bilharzi 
