The Conchostraca of the Cambrian Area of Comley, Shropshire, with a note on a New Variety of Atops reticulatus Walcott

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Abstract
The principal object of this paper is to record species of Conchostraca that have been left over from my previous communications for more detailed study. Opportunity is also taken to record a specimen of Atops reticulata (Walcott) var., and thus to complete my account of the Cambrian faunas of Comley. The index letters for the horizons used in this paper are those set out in my paper of 1921 (table facing p. 326). An index to the exposure numbers will be found in my 1927 paper (p. 553). In the study of these fossils I am much indebted for guidance to the work of Drs. Ulrich and Bassler (1931), and I have followed their classification and, to a great extent, their nomenclature and method of description. It is most important, in dealing with these small fossils, to give a clear statement of their form. In the following pages the method generally adopted is : first, a note on the hinge-line; then, in consecutive order, the antero-dorsal angle, the anterior curves, the ventral curves, the posterior curves to the post-dorsal angle and hinge-line. The term “length” indicates the greatest extension parallel with the hinge-line; the “greatest length” (when necessary) is a measurement diagonally across the valve; “depth” is the extension at right angles to the hinge-line; “thickness,” the measure of the test may be smooth, punctate (like sharp needle punctures), pitted (relatively large punctæ), granular, tubercular, or scabrous. This last term is used when the test appears to have been broken

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