File:American malacological bulletin (1988) (17535886603).jpg

Title: American malacological bulletin
Identifier: americanmal6719881990amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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TAN TIU: POLYMESODA CAROLINIANA SHELL MICROSTRUCTURE 203 are sometimes not aligned, such that the tertiary lamellar tips protrude at varying lengths into the central space of the cir- cular structure. Therefore, the shape of the spaces enclosed by the secondary lamellae vary depending upon the degree of curvature of the secondary lamellae. Seasonal and habitat variations in the microstructure of the inner shell surface of caged and uncaged Polymesoda caroliniana are summarized in Table 3. Over the 13 month period, microstructure C in wild clams was absent in June of 1985 and 1986, and its frequency of occurrence peaks in March 1986 (Table 3). The frequencies of occurrence of the following microstructures were highly correlated (r > critical values at ra05(2)3 = 0.878) in wild clams: microstructure C negatively correlated with crossed-lamella one and complex crossed-lamella one. Other microstructures of the inner shell surface did not show distinct seasonal patterns. Microstruc- ture C was negatively correlated, whereas complex crossed- lamella one (r = 0.941) was positively correlated significantly with temperature of surface water at the time of sampling than the temperature average per season. During the four seasons over the 12 month period, microstructure C in submerged clams was absent in September 1985 and June 1986, but its frequency of occur- rence also peaks in March 1986 like that of wild clams (Table 3). Frequency of occurrence of crossed-lamella one was negatively correlated with that of microstructure C. Other microstructures of the inner shell surface did not show distinct Table 3. Temporal and spatial variation of internal shell surface microstructure in Polymesoda caroliniana, Jackson County, Mississip- pi. Headings stand for areas of shell examined (first row) and shell microstructural type (second row). Shell microstructure abbreviations are: C, microstructure C; CL, crossed-lamella: CCL, complex crossed- lamella; Ret, reticulate. Frequency of occurrence expressed in per- cent, where 0 = 0%, 1 = 1 to 20%, 2 = 21 to 40%, 3 = 41 to 60%, 4 = 61 to 80%, 5 = 81 to 100%. Area A Areas B-C Areas G-l C CL1 CL2 Ret CCL1 CCL2 CCL3 Ret Rod and Reel Fishing Camp (wild) June 1985 0 5 5 0 1 0 5 0 Sept 1985 1 5 5 1 1 3 2 1 Dec 1985 2 3 5 0 0 3 3 1 Mar 1986 3 3 5 1 0 2 1 3 June 1986 0 5 5 0 1 1 1 3 Submerged Area (caged) Sept 1985 0 5 5 0 2 3 1 1 Dec 1985 1 4 5 1 1 2 2 2 Mar 1986 3 3 4 1 1 2 2 3 June 1986 0 5 5 0 1 1 1 4 Exposed Area (caged) Sept 1985 1 5 5 0 0 2 2 2 Dec 1985 3 3 4 1 0 3 0 3
Text Appearing After Image:
Fig. 6. Complex crossed-lamella one (HFW = 22 ^m). Fig. 7. Complex crossed-lamella two (HFW = 22 ^m). Fig. 8. Complex crossed-lamella three (HFW = 22 Mm). Fig. 9. Reticulate microstructure (HFW = 22 Mm).

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