tortoiseshell

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tortoiseshell 

Material used in the manufacture of spectacle frames. It is obtained from the shell plates of the hawksbill turtle. See plastic spectacle frame; spectacles.

tortoiseshell

a coat color in cats consisting of a mixture of black and shades of red to yellow, usually broken into large patches. The color can be found in a variety of cats, both long- and shorthaired, and specific breeds, such as Burmese. Tortoiseshell-and-white is another variety, called calico in the USA and chintz in the United Kingdom. Because the genes for black and orange (including shades from red to yellow) are carried on an X chromosome, but not the same one, only females can carry both colors. Males from similar breeding are either orange or black. There are isolated examples of tortoiseshell or tortoiseshell-and-white male cats, but almost all are sterile due to the chromosomal abnormality of XXY. These are considered models of the human condition, klinefelter's syndrome. Rarely, the phenomenon may be attributed to somatic mutations, crossing over of chromosomes or mosaicism.
References in periodicals archive ?
In an even more surprising development, the scarce tortoiseshell - which as its name suggests is extremely rare - appeared in the UK for the first time since 1953.
More than 20 sightings of the butterfly, also know as the yellow-legged tortoiseshell, were reported in several counties, mainly along the east coast around Norfolk but also as far as Tyneside, the charity said.
The large tortoiseshell, meanwhile, was lost as a breeding species in the UK more than 40 years ag o, but this year was regularly seen in southern England during the summer.
The mild weather, even during last winter, and lack of drought was good for stinging nettles which the tortoiseshell larvae feed on.
PERENNIAL asters or Michaelmas daisies flower from July to September and all but the double varieties will attract painted lady and small tortoiseshell into the garden.
THE sweet, fruity smell of buddleia flowers attracts swarms of butterflies such as peacocks, red admirals and small tortoiseshell - so much so it is nicknamed "the Butterfly Bush".
SCABIOUS The scented pin-cushion-like heads of scabious attract small tortoiseshell, common blue, skippers and holly blue butterflies.
Flutter forward the small tortoiseshell butterfly which took things a bit too far by emerging from hibernation in a sheltered West Kirby garden on January 25.
Once a small tortoiseshell emerges, its first instinct is to breed, rather than feed,but I suspect that cold nights mean the ``West Kirby One'' has already gone to the great nettle patch in the sky without meeting the partner of its dreams.
Dahlia-free January is an unwelcoming place for small tortoiseshell butterflies