periostracum


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periostracum

the outermost of the three layers of the shell of molluscs or brachiopods, composed of CONCHIOLIN. On the inner side lie the prismatic layer and the nacreous layer.
References in periodicals archive ?
These mussels attained moderately large sizes as adults, ranging from 5 to 7 cm in valve length, and had a thick black periostracum similar to that observed for mussels in the Mytilus edulis species complex found in more northern waters of Asia (Inoue et al.
Though much of this material is clearly old, some specimens were of fresh appearance and retained the periostracum, indicating that the species is probably still extant at the site, even though we found no live specimens during our survey.
Bonetto and Ezcurra (1965), studying the sculptures of the periostracum of species from the genus Anodontites, grouped A.
The shell of Haliotis discus hannai Ino is polycrystalline composites of calcium carbonate and proteins and glycoproteins and consists of the periostracum, prismatic and nacreous layers with calcite in the outer prismatic layer and aragonite in the inner nacreous layer.
68) well-preserved when found but extremely fragile, sinistral, thin, globose, spire obtuseconical, body whorl extremely inflated (Harmen & Berg 1971); subfossils lacking periostracum.
Etter 1988), the presence or absence of periostracum on molluscs (larger Mytilus sp.
Although values of [Alpha] (short-wave solar absorptivity) could potentially change with shell characteristics (such as eroded periostracum or heavy diatom cover) a value of 0.
The outer surface of each shell was sanded to remove periostracum and ridges and produce surfaces of equal roughness.
The external valve surface shows clear growth lines and the periostracum is not persistent, allowing prism cross sections to be readily discerned.