>Dear Andrew,
>
>Nice to hear from you again.
>
>Yes, actually, the shell was living in my 'unidentified Rissoid'
>file until I pulled it out. And at about 12mm it is simply much too
>big and wide to be a juvenile Rissoid, epecially since the largest
>Rissoid I know of, R. gigantea, grows to about 20mm, but is much
>more narrow and has a different shape altogether
>
>I think we need to keep guessing
>
>Patty

Hi Patty

I stick by Rissoininae.

It may be geronitic and/or abnormal (parasitized?); note the change
in whorl profile and ribbing. The spiral cord is real, not caused by
missing bodywhorl; the labrum shows a corresponding notch.

Gastropods with parasitized gonads may keep on growing far longer
than normal (interruption of normal growth-hormonal scheduling),
becoming giants.

On top of this, it may well be undescribed. Have you asked Barry Wilson etc?
--
Regards
Andrew