Dhondtichlamys trigeminatus (Goldfuss, 1833)
GOLDFUSS, A. 1833-1840. Petrefacta Germaniae tam ea, quae
in museo universitatis regiae Borussicae Fridericiae Wilhelmiae Rhenanae
servantur quam alia quae cunque in museis hoeninghusiano, muensteriano aliisque
extant, iconibus et descriptionibus illustrata. Zweiter Theil, 1-312 p., pls.
1-199. Arnz & Co., Düsseldorf. [p. 52, pl. 91, fig. 14]
A. Goldfuss, 1833, plate 91.
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Pecten testa ovato-acuta convexo-plana laevi, costis fasciculatim ternatis mediis maioribus, sulcis plano-concavis, auriculis inaequalibus subplicatis. — E creta virescente Westphaliae. M. B. et M. M.
Spitzig-eiförmig, flach-convex, glatt, mit büschelförmig-aus strahlenden convexen Rippen. Je drei derselben, von welchen die mittlere die grösste ist, bilden einen Strahl. Die Zwischenfurchen sind glatt und die ungleichen Ohren streifig und schwach gefaltet. Die grosse Höhe und die Abrundung der mittlem Rippen unterscheiden diese Art von der vorhergehenden. — Sie findet sich in der grünlichen Kreide zu Lemförde und Haldem bei Osnabrück.» AUGUST GOLDFUSS, 1833
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«Description:
Flattened, prosocline shell with well developed unequal auricles; 11 groups of 3 ribs start at the umbo and continue straight towards the pallial margin; the intercostal intervals are almost as broad as the ribs and on their lowest part are 2 slightly elevated radial riblets; all ribs are smooth. Anterior auricles: large and rectangular with straight outer margin; no macrosculpture. Posterior auricle: rectangular and smaller. Discussion
The specimen from the I. R. Sc. N. B. differs from the specimen described by GOLDFUSS in being of a more prosocline appearance and in having two intercostal riblets.
These differences can be explained : 1. The posterior side of the valve from Maastricht is partly broken off; this would explain the prosocline shape. 2. The intercostal riblets could occur in left valves and not in right ones (the specimen from Maastricht is a left valve, but GOLDFUSS's specimens are right valves). The species seems to be extremely rare and is not sufficiently known. It can be differentiated from — L. (A?) ternatus by the smoothnees, number and distribution of the ribs and by its smooth auricles. — from the other L. (A.) -species on the same grounds as those stated in the description of L. (A?) ternatus. Generic attribution: The rib distribution in Pecten trigeminatus GOLDFUSS is fairly different from the other Lyropecten (Aequipecten) species; the general shape is slightly more elongated. This explains the doubt as to the generic attribution of the present species.» DHONDT, A. V. 1972. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 2: Lyropecten. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, 48 (7): 1-81, pls. 1-3. [p. 58, 59]
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Lyropecten (Aequipecten?) trigeminatus (A. Goldfuss, 1833); A. V. Dhondt, 1972, Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous, Part 2: Lyropecten, plate 3, figure 2.
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