>The way I originally interpreted the question, I thought Eduard was asking
>for two very similar species in two different families respectively.

There are two nonconspecific species here in NZ which cannot be
separated on shell characters if the protoconchs are missing. One is
a cerithiopsid, the other a metaxiine triphorid. It's a pain, as I
have quite a few specimens of this pair missing protoconchs, and
labelling/cataloging with the species "this OR that" is not
convenient.

Of course it could be argued that Triphoridae and Cerithiopsidae are
not really distinct anyway...
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut