118 S. S. Buckman— Paleontological Nomenclature. 
3.—He suggests that the trinomial system would obviate the 
necessity of any of these changes and be at the same time an 
advantage. 
In regard to the first point, I would remark that probably no 
change of any kind, however necessary. can be made without 
disturbing those who have been accustomed to other ways, and 
therefore, it is right that those who make these changes should give 
some reason for so doing. It can be urged that scarcely has the 
sound of the protests raised against the subdivision of the genus 
Ammonites died away, but the proposal to still further subdivide the 
subdivisions is started, and everything is again unsettled. But I 
would ask if paleontology is to follow, and be subject to, the same 
laws and conditions which govern other sciences, viz. entomology, 
botany, etc.? Is a genus to be considered as a name for a series of 
species having certain characteristics in common which at the same 
time separate it from other series? Is it not wrong to include in 
the same genus species descended for a long time through entirely 
different lines of ancestors? But do the present generic names 
satisfy these conditions? Does Harpoceras, which included such 
very different Ammonites as bifrons, insignis and Levesquet, 1.e. 
Ammonites descended from the old families Arietes, Armati, and 
Vatrices, of the Lias, fulfil the conditions of a genus? It cannot; 
and, therefore, I contend that it is necessary that the range of a 
genus should be narrowed. I place in the same genus Ammonites 
bifrons and Levisoni which agree in being very evolute, in having an 
identical suture-line, and quadrangular whorls with furrows on each 
side of a solid carina, but differ from each other specifically by a 
persistent but slight difference in ribbing. On the other hand, I 
decline to put into that genus Ammonites which have sagittate 
whorls, a different suture-line, and a hollow carina. As regards 
the difficulty of remembering all these names, I would point out 
that this is no more than we meet with in other sciences, and any 
disadvantage in this way is fully compensated by the advantage 
that we obtain by expressing a definite idea regarding a certain 
number of species. The number of genera in other sciences gives 
us sufficient excuse. For instance, in the division Geometers of the 
Lepidoptera we find, in Britain, about 200 species divided into 17 
families and 88 genera. 
Concerning the second part of Mr. Haddow’s letter, I do not con- 
sider myself to blame for the confusion of which he speaks. He 
asks whether the “well-known specific names cannot be applied in 
a sufficiently comprehensive way to include the forms which the 
older authorities recognized under the names A. serpentinus, A. jurensis, 
and A. Sowerbyi, respectively ?”” But who are the older authorities in 
this matter? Surely they are those who in the first place imposed 
these names on certain definite species which they figured, and are 
we to perpetuate a mistake because since then certain authors and 
collectors have entirely mistaken the identity of the fossils so named ?. 
Mr. Haddow supposes, I fancy, that the species which the later 
authors had in view are merely varieties of what the older authors 
