Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 70. (Budapest 1978)

Vörös, A.: Viallithrys gen. n. (Terebratulida, Brachiopoda) from the Mediterranean Lower Jurassic

Viallithyris gozzanensis (PARONA) (Plate I: 1-6, Figs. 1-5) 1880: Terebratula Gozzanensis n. sp. — PARONA, GOZZANO, p. 196., pl. L, rig. 8. 1880: Terebratula Sismondai n. sp. — PARONA, Ibid., p. 197., pl. I., fig. 9. 1884: Terebratula Engeli HAAS-HAAS, Südtyrol und Venetien, p. 22., pl. III., figs. 3-5. 1885: Terebratula (Pygope (?)) Gozzanensis, PAR.-PARONA, Saltrio e Arzo, p. 252., pl. V., figs. 1-2. 1893: Terebratula Gozzanensis, PAR.-PARONA, Revisione, p. 42., pl. IL, figs. 14-17. 1898: Terebratula Gozzanensis PARONA-BÖSE, Östlich. Nordalpen, p. 165., pl. XL, figs. 8, 10-12. 1900: Pygope gozzanensis PARONA-BÖSE & SCHLOSSER, Südtyrol, p. 184., pl. XVII., figs. 5, 9, 10. 1967: "Terebratula''' gozzanensis PAR.-SACCHI VIALLI & CANTALUPPI, Nuovi foss. Gozzano, p. 97., pl. XV., figs. 1-3., text-figs. 22-23. Material: 194, partly incomplete specimens. Dimensions: The length, width and thickness data of 73 measurable specimens are presented in Figs. I

. and 2. Description. External characters: V. gozzanensis is a medium to large sized terebratulid, subpentagonal to subcircular, rarely oval in outline. Both valves are moderately, nearly equally convex; the maximum thickness is attained at about the middle of the length. The lateral commissure is sulcate but tends to be rectimarginate in the juvenile specimens. The form of the sulcation varies from a wide, flattened, angular deflexion to a simple, low sinus. In adult stage the valves meet at an obtuse angle; exceptionally, concave surfaces may develop along the lateral commissures. Distinct sinus and fold are not discernible. The surface of the shell shows weak and irregularly spaced growth lines; the well-preserved specimens are finely capillate. — Internal characters (Figs. 3-4): Pedicle valve: The delthyrial cavity is circular to subtrigonal in cross-section. The pedicle collar is well developed, rather long. The deltidial plates are thin and fused, forming a symphytium. The hinge-teeth are moderately long and laterally expanded: crenulation is not developed. The outline of a narrow and long muscle scar is clearly visible in the cross-sections. — Brachial valve: The cardinal process Fig. 2. Variation of thickness (T) against length (L) of 73 specimens of Viallithyris gozzanensis (PARONA)