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Date: | Fri, 16 Jan 2004 06:32:42 -0800 |
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Thanks Andrew,
So this feature is actually the shell structure? I think I was misleading
by using the term 'nacre' (I apologize). What I meant is the actual
surface "feel" of the shell... which you explained with the term "shagreen".
So does Cypraea (Umbilia) armeniaca also have this shagreen sculpture? If
not, why? :)
Nancy Smith
§ -----Original Message-----
§ From: Andrew Grebneff [mailto:[log in to unmask]]
§ Sent: 16 January, 2004 0:44
§ To: [log in to unmask]
§ Subject: Re: Cypraea question: Umbilia nacre
§
§
§ >I have several specimens of C. hesitata, as well as h. beddomi and
§ >h. capricornica and wondered about the nacre of these shells...
§ >The pictures I've seen of C. armeniaca appear to have a 'typical'
§ >glossy nacre (typical of many Cypraea anyway) but the hesitata, h.
§ >beddomi and h. capricornica have what I would describe as a "matte"
§ >finish to their nacre. Why are they different in this way, while
§ >all are members of Umbilia? Or does C. armeniaca have a
§ matte-like
§ >finish as well?
§
§ Cypraea inductura ("callus"), I think you will find, is smooth down
§ to a microscopic level. That of Umbilia (one of the few good genera
§ in the family) probably have what is called shagreen
§ sculpture, which
§ consists of small anastomosing pustules etc; in some gastropods this
§ is large enough to be naked-eye-visible; in others it's microscopic.
§
§ From memory some volutids and olivids have visible
§ shagreen sculpture.
§
§ Strictly speaking nacre is so-called mother-of-pearl, as found in
§ triochids, pleurotomariids etc.
§ --
§ Andrew Grebneff
§ Dunedin, New Zealand
§ 64 (3) 473-8863
§ <[log in to unmask]>
§ Fossil preparator
§ Seashell, Macintosh & VW/Toyota van nut
§ ________________________________
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§ ________________________________
§ Opinions in this e-mail are my own, not those of my institution
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