a Pedicle [foramen] [Hinge line] b Pedicle [valve] Beak Brachial valve
CLASS INARTICULATA.—
The members of this class are rather primitive and have a long geologic history. These brachiopods have valves which are not provided with hinge teeth, the valves being held together by muscles, and a [hinge-line] is lacking ([fig. 14]). Most inarticulate brachiopods are circular or tongue-like in shape and commonly composed of [chitinous] and [phosphatic] material. Inarticulate brachiopods range from Lower [Cambrian] to Recent in age but were never as common as the articulate brachiopods, which are described below. Brachiopods belonging to this class have been recorded from several [Paleozoic] formations in Texas ([Pl. 17], Lingula, Apsotreta, Angulotreta).
Plate 17
[PENNSYLVANIAN] BRYOZOANS
FISTULIPORA × 6 POLYPORA × 5 RHOMBOPORA × 8
[CAMBRIAN] BRACHIOPODS
APSOTRETA × 10 LINGULA × 4 ANGULOTRETA × 10