Dear John,

a "perspective" umbilicus in Gennaeosinum Iredale, 1929 clearly means a "see
through" umbilical cavity, in the sense that you can see all the way up to
the apex (not through the shell layer of the apex, though!). Once you hold a
Gennaeosinum in your hands, you immediately understand what exactly the word
is supposed to mean.
This peculiar wording did not originate with Barry Wilson but rather was
copied by him from the 1929 original description of the genus Gennaeosinum
by Tom Iredale in the 'Memoirs of the Queensland Museum' 9(3):280. Iredale
stated, among other things: "Umbilicus large, open, perspective, funicle
running up."
The genus Gennaeosinum is regarded by some (Kabat 1991, Bull. Mus. Comp.
Zool. 152(7):430) as a junior synonym of Sigatica Meyer & Aldrich, 1886.
Unfortunately, aside from an "authoritative statement" no evidence was
offered to support this opinion.

Michael



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Prof. Dr. Michael Hollmann
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