342 Remarks on the Genus Paradoxides of Brongmart. 
ters are, that the animals should be blind, and that the arches of the 
lobes, and especially those of the tail, should be prolonged beyond 
the membrane which sustains them. But notwithstanding these re- 
marks, and doubtless from a desire not to multiply names, Professor 
- Brongniart has introduced into his genus Paradoxides, from draw- 
ings, three animals, which bear a very faint resemblance to those on 
which it was founded ; these fossils he names P. scaraboides, P. 
gibbosus, and P. laciniatus. The first has an expanded tail, some- 
what like an Asaph; the second has no prolongation whatever of 
the lateral and caudal arches, and the third is supposed to be fur- 
nished with eyes. I have but little doubt that Prof. Brongniart will 
exclude these fossils when he comes to examine them for himself 
from his otherwise natural genus Paradoxides, in some future edition 
of his most admirable work. 
The practice adopted by some of amending, modifying, or in 
some essential point, altering the generic characters of one author to 
adapt them to new animals discovered by another, I suppose to be 
altogether inadmissible and contrary to the established canons of a 
correct nomenclature. 
I have been led to these remarks in consequence of some recent 
attempts to force my genus Triarthrus into that of Paradoxides. It 
is not pretended, I believe, that the animal remain I have described 
as Triarthrus Beckii, bears the most distant resemblance to the P. 
spinulosus or the P. tessini, the only true Paradoxides of Brongni- 
art, but that the head, according to one author, is like that of the P. 
scaraboides, and the tail, according to another, is similar to that of the 
P. gibbosus. It is obvious that by such a process of compression 
and amalgamation, of decapitation and curtailment, all generic dis- 
tinctions would be of little value. y 
It is one of the fixed principles of nomenclature among natural- 
ists, that the first name applied to a genus, should be invariably re- 
tained, and that the author himself of the genus should not be allow- 
ed, without the most cogent reasons, to infringe this law. From the 
great accumulation of species, and from the new discoveries with 
regard to old ones, in fossil zoology, it is plain that if we adhere to 
the genera as first established, and create no others; or if, on the 
plan of Fabricius, we make subdivisions of them, by introducing new 
characters to adapt them to new objects, then the genera will not 
only be overloaded, so as to be comparatively useless, but they will 
necessarily embrace animals very imperfectly characterized. Again, 
