Hello hello

The two mediterranean Rissoidae Alvania discors (Allan, 1818) and Alvania
lineata Risso, 1826, are considered as different species by CLEMAM and my
Poppe & Goto... I am not aware of the last updates in the Rissoidae
knowledge, (the Atlante etc.) and I suspect that these two shells are
synonyms, or often misidentified, confused, etc.

Any idea of the distinctive features which could separate discors from
lineata ?
I have 3 samples of these species, and they look exactly indentical, so what
?


By the way, a grammatical question:
Which, That... I read sometimes sentences that use "which" and "that"
indifferently,as this last one. Is this right ?

I understand that, between these two sentences : "the thing that I hold",
"the thing which I hold", the first is correct and the second must be thrown
away, but...
Between these two : "the thing that is", "the thing which is", which one is
the better in US in GB etc ?

Any help welcome

regards

Olivier Caro

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