Horrible keys

Richard Jensen rjensen at SAINTMARYS.EDU
Thu Aug 31 08:31:06 CDT 1995

I disagree with Murray Fletcher's view that any couplet having "not as
above" is a poor couplet.  Some (many, most?) taxa are polythetic entities
or are especially variable in individual characters - a simple way to
isolate them in a key (rather than following them through all possible
leads) is to specify the combination of characters that allows
identification.  As long as no other taxon in the key has that precise
combination of features, then the couplet works, and that's one key to a
good key.

Richard J. Jensen      |   E-MAIL: rjensen at saintmarys.edu
Dept. of Biology       |   TELEPHONE: 219-284-4674
Saint Mary's College   |   FAX: 219-284-4716
Notre Dame, IN  46556  |

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