Shell structure of the Galapagos Rift limpet Neomphalus fretterae McLean 1981, with notes on muscle scars and insertions. American Museum novitates ; no. 2776

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New York, N.Y. : American Museum of Natural History
"The principal shell layers of Neomphalus fretterae McLean, 1981, are an inner concentric crossed-lamellar and an outer complex crossed-lamellar layer. The protoconch is unusual in being composed of four layers rather than one or two as in most other gastropods. The narrow, high-angled crossed-lamellae of the inner principal layer are nearly identical with those of advanced mesogastropods, rather than the broader, low-angled archeogastropod crossed-lamellae. This, along with shell shape, ornament, and the presence of a muscle platform suggests a closer relationship with the mesogastropod limpets than with the archeogastropods. Muscle attachment is by direct muscle fiber insertion, forming tubules in the shell, and also by myo-adhesive epithelial cells which may form a myostracal layer. Based on the multiple layers found in the protoconch, I speculate on the possibility that the larval stage may have remained planktonic for an extended period"--P. [1].
13 p. : ill. ; 26 cm.
Includes bibliographical references (p. 12-13).