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beets, c.

AuthorC. Beets
TitleOn Waisiuthyrina, a new articulate Brachiopod genus from the upper-oligocene of Buton (S.E. Celebes), Dutch East Indies
JournalLeidse Geologische Mededelingen
AbstractMaterial: one well-preserved entire shell and another one, of which the ventral valve was destroyed for the greater part for the sake of chemical analysis in the „Rijkswegenbouw-Laboratorium”.
Dimensions: the ventral valve of the holotype (fig. 9) has a length of 48.2 mm from the posterior or cardinal to the anterior border; the dorsal valve (fig. 8) is 45.2 mm long. The dorsal valve of the paratype (fig. 16) has a length of 53.8 mm. The breadth of the type is 49 mm, the thickness 32.6 mm. The habitus is more rhynchonelloid than terebratuloid, as e. g. in Gryphus Cubensis (Pourtalès) or Abyssothyris Thomson, 1927, or in some cretaceous groups (cf. Sahni, 1925). The shell is exactly bilaterally symmetrical, the ventral (pedicle-) valve being somewhat larger than the dorsal one, with more prominent umbo, but the dorsal valve is more convex than the ventral (figs. 11—12). This type of shell-shape was named dorsibiconvex by Schuchert and Cooper (cf. McEwan, 1939, p. 617—618: follow the evolution-line on the right in the diagram, the line of dorsitumid shells). As McEwan has pointed out, this and other types of the shape of brachiopodal shells may serve as reliable bases for systematical division (as was also recommended by other students); in the key to families given by McEwan (l. c, p. 620) we come, in combination with the characteristics of hinge, deltidium, foramen, shape and sculpture, to the place II-A-1-b among the Telotremata; we cannot reach the finest division as the branchial skeleton of this species is not visible.
Document typearticle
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