Good points, Paul.

Sometimes a drawing is the best type specimen. For a long time, methods of
preservation were inadequate for most groups of animals, and a drawing
could actually last longer than the type specimen. Some animals shrink and
distort badly in preservative fluids, and most lose their color. Important
skeletal elements may dissolve. Nudibranchs can only be properly
appreciated when alive, or in photographs or drawings.

T. A. Conrad's methods of diagnosis deserve a mention. I've heard him
castigated because of his brevity, but the style at the time was to make
diagnoses short and to the point. Linnaeus himself said that a diagnosis
should take up no more than 13 words (in Latin; English tends to use more
words per thought than Latin). One method of cutting out words was not to
repeat generic characters in the diagnosis of a species, which puts the
burden on the reader to know the genera well before reading about new
species. Conrad's diagnoses are spare, but elegant: He often captured the
essence of the taxon as it is understood even now. Some of his
contemporaries also produced brief diagnoses, but many are based on
unimportant or variable characters, and some are quite meaningless.

Here is a typical Conrad diagnosis, of the Eocene gastropod Oliva
alabamensis Conrad, 1833:

"Shell subfusiform, spire conical, acute, the whorls contracted, and
defined by an impressed line above the suture. Length 1-1/2 inches."

Breathtakingly brief, isn't it?

That is, "Oliva alabamensis is a new species of Oliva whose shell is shaped
rather like a spindle (subfusiform), and whose spire is conical. [That is,
the shell bellied out as the animal grew older.] The apex is sharply
angular (acute). Each whorl covers much of the last one (contracted), with
a narrow groove (impressed line) where the whorls touch (suture)." That's a
lot to squeeze into one sentence, but the specialized terms help. It's not
particularly easy to read, but the fact is that the diagnosis has stood the
test of time. The species has been transferred to genus Agaronia, but it is
still understood in about the same way.

Andrew K. Rindsberg
Geological Survey of Alabama