Comprehensive Description

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Description

"Genus Parasmittina, new genus

 

 

Avicularia variously distributed on the frontal, but never median, suboral and bilaterally symmetrically developed around the proximal border of the aperture; they take their origin from areolar pores on one side. The frontal is a pleurocyst with a row of areolar pores and occa¬sionally there are some additional pores, usually at the proximal end; the lyrula and cardelles usually well developed, though the overhanging peristome in some cases may require dissection to expose them. The ovicell is variously perforated, by numerous small pores, by several larger ones which may vary in size and form, or more rarely by 1 to 3 central pores. Genotype, Lepralia jeffreysi Norman, 1876:208.

 

The essential differences between this group and Smittina (sens str.) arc in the nature of the frontal and the avicularia. The frontal is a Pleurocyst, and even in the occasional zooecia which have additional pores inside from the areolar row the pleurocystal layer is seen to develop from the border toward the center; young marginal zooecia show this manner of growth, especially after incineration. The avicularia are various in size, form and distribution, but the chamber is never bilateral; they may be oval, spatulate, short-triangular or long-pointed and range from minute to gigantic, and they may sometimes be interzooecial; not infrequently there may be several forms and sizes on a single zooecium; they often vary greatly on the same zoarium." (Osburn, 1952: 411)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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