Hola APower:
 
It could be that Gmelin get a box of shells from some place and when he saw them
he came to the conclusion that several of them where Nerita; when he look hard on
these he divided them in two lots; the critters in each lot looked alike to him,
but he thought that there were significant differences between the two lots; then
he named two species. Then the years passed away and more and more shells were
found, some of them intermediates between the two lots, filling the gap and making
a continuum. Then some other guy said that there was only one species with enough
variation to confound Gmelin.
 
It is very difficult to define a species because the notion of species is human;
it was defined prior to Darwin and Mendel, and animals did not go to the
university to study it.
 
But it has been very useful to help understand the animal world; with time you are
going to get used to the several problems about this idea and the more problems
that we, humans, produce when try to do a taxonomia. We are not perfect and our
system is not perfect; I think we are on the brink of changing the binomial system
for a new model to classify living beings; probably the binomial will last as the
Newtonian ideas last, because it is useful.
Saludos
Emilio
 
APowersjr escribis:
 
>   Once again I'm stuck. I received great help on- species and syn: ( about
> nerites )
>   I have Nerita atra ( Gmelin,1791 ) it has a  Syn: senegalensis ( Gmelin,1791
> )
>   I understand a syn: being the same shell with a different author, but here
> we
>   have the syn with the same author with the same year. Should I be looking
> for
>   the syn: being a different nerite, or did he forget he already named the
> nerite a
>   week before.
>   Thanks again for the help
>                              Jr