. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. Figs. 3-5.—Ventral pallial and ovarian markings. 3, Orthis s. s.; this type characterizes the family Orthidae as here described. 4, Schizoramma, in which the markings are essentially the same as in Orthis and Hesferorthis. 5, Dinorthis (PUsiomys) subquairata (Hall); notice here that the main trunks extend from the anterior of the diductor scars. In the ventral valve the pallial trunks in all orthoid brachiopods begin at the same place. genera of Atremata {Obolus, Lingulobolus,
. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. Figs. 3-5.—Ventral pallial and ovarian markings. 3, Orthis s. s.; this type characterizes the family Orthidae as here described. 4, Schizoramma, in which the markings are essentially the same as in Orthis and Hesferorthis. 5, Dinorthis (PUsiomys) subquairata (Hall); notice here that the main trunks extend from the anterior of the diductor scars. In the ventral valve the pallial trunks in all orthoid brachiopods begin at the same place. genera of Atremata {Obolus, Lingulobolus, Lingulella, Bicia, Dicellomus) and of Neotremata {Obol- ella, Acrothele, Botsfordia, Acrotreta). Accordingly these markings should be common among the Cambrian Orthacea, and so they are. They are especially well seen in BilUngsella. In living brachiopods, according to Thomson,^' The pallial sinuses take the form of great trunks, entering the mantle-lobes from the coelome, and generally branching repeatedly towards the margins. The disposition of the sinuses varies considerably in different groups, and it is probable that these characters have at least super family value in classification. The pallial marks have been found of great use in defining some of our families. In general, the pallial markings of the ventral valve are rather simple as regards the main trunks. Their general arrangement is foreshadowed in the Cambrian genera of the Billingsellidas in the two prominent trunks which radiate antero-laterally from the forward ends of the diductor scars, thence splitting and diverging toward the front and sides of the valve. One of the anterior branches of each trunk swings dorsally and runs nearly parallel to the lateral margin. The other, shorter branches extend inward and may or may not unite near the mid-line of the valve (see pi. 1, fig. 10). ^'Amer. GeoL, vol. 19, 1897, p. 93. »«Brach. Morph., 1927, p. Please note that these images are extracted from scanned pag
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