On the variation of the shell of Pecten Irradians Lamarck from Long Island

Davenport, Charles Benedict (November 1900) On the variation of the shell of Pecten Irradians Lamarck from Long Island. The American Naturalist, 34 (407). pp. 863-877.

URL: http://www.journals.uchicago.edu/doi/abs/10.1086/2...
DOI: 10.1086/277807


The right or lower valve of P. irradians has on the average half a groove more than the upper, because the series of alternating ridges and grooves of the right valve has a prevailing tendency to end in grooves. Of three Long Island localities, the most nearly land-surrounded shows Pectens with the greatest number of rays. The right valve is less variable than the left, a result which agrees with the fact that the right valve of Pectens is generally more archaic than the left. The variation is nearly normal in both valves; more so in the left than in the right valve. The skewness is positive, showing a slight tendency towards an excessive production of the many-rayed individuals, or the selective annihilation of those with few rays. This positive skewness is paralleled by the fact that P. irradians seems to be developing towards a larger number of rays. The various abnormalities of Pecten are either explained as self-adjustments to accidents or as sports which represent typical conditions in allied species.

Item Type: Paper
Subjects: evolution
CSHL Authors:
Communities: Station for Experimental Evolution at Cold Spring Harbor
Depositing User: Matt Covey
Date: November 1900
Date Deposited: 17 Jan 2013 15:41
Last Modified: 01 Nov 2017 14:57
URI: https://repository.cshl.edu/id/eprint/26520

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