. Bulletin. Natural history; Natuurlijke historie. 32 PATELLOID AND BELLEROPHONTOID SHELL STRUCTURE. Text-fig. 35.—Oblique view of inner surface of radially sectioned shell of Patella mexicana show- ing wavy structure of second-order lamellae in concentric crossed-foliated layer (m -\- 2). A, enlargement of part of ventral surface of shell showing light-dark pattern caused by two different reflection-angle sets in the wavy structure. B, enlargement (see PI. 14, fig. 3) showing angle of wave-flank intersection with dip plane of second-order lamellae. Based on hypotype, UCMP no. 36487. Complex C
. Bulletin. Natural history; Natuurlijke historie. 32 PATELLOID AND BELLEROPHONTOID SHELL STRUCTURE. Text-fig. 35.—Oblique view of inner surface of radially sectioned shell of Patella mexicana show- ing wavy structure of second-order lamellae in concentric crossed-foliated layer (m -\- 2). A, enlargement of part of ventral surface of shell showing light-dark pattern caused by two different reflection-angle sets in the wavy structure. B, enlargement (see PI. 14, fig. 3) showing angle of wave-flank intersection with dip plane of second-order lamellae. Based on hypotype, UCMP no. 36487. Complex Crossed Structures These structures include the complex crossed-lamellar structure of B0ggild (1930) and the complex crossed-foliated structure, a term proposed here for what Wada (1963a, 1963b) described as a spiral growth phenomenon in the calcitic foliated layers of some pelecypods. The complex crossed structures can be described most simply as a cone-in-cone (see glossary) arrangement of crystal Text-figs. 36-38.—Idealized diagrams of elements of a major prism of the complex crossed-lamel- lar structure. Explanation of symbols: a, cone apex; ad, apparent dip angle; b, median bisect- ing plane of major prism; c, central axis of major prism; g, growth line; m, cone margin; r, rhomboidal prismatic segment of third-order lamella; s, conical second-order lamella; t, third-order lamella; td, true dip angle of conical second-order lamellae; ts, thin section. 36, single conical second-order lamella. 37, section along central axis of major prism showing chevron pattern of second-order lamellae. 38, section on flank of major prism parallel to central axis; A, enlarged rhomboidal prism representing the part of a third-order lamella in thin section (ts).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peabody Mu
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