Lyriochlamys henrici Dhondt, 1973
DHONDT, A. V. 1973. Systematic revision of the Chlamydinae (Pectinidae, Bivalvia, Mollusca) of the European Cretaceous. Part 3: Chlamys and Mimachlamys. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique, 49 (1): 1-134, pls. 1-9 [p. 99, pl. 5, fig. 2]
1973 Mimachlamys henrici Dhondt, 1973
A. V. Dhondt, 1973, plate 5.
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«. 1896 - Pecten cf. Puzosianus A. J. JUKES-BROWNE & W. HILL, p. 151.
v. 1902 - Pecten (Chlamys) Puzosianus H. WOODS, pp. 165-166, pI. 30, f. 9 a, b, 10 a, b, 11, 12. ? (1927) Chlamys Puzosi E. KAHRS, p. 633. . 1961 Chlamys (Chlamys) puzosianus V. A. SOBETSKI, pp. 29, pI. 2, f. 1, 2. . 1968 Chlamys (Chlamys) puzosiana S. I. PASTERNAK et aI., p. 155, pI. 32, f. 1-2. non 1842 Pecten puzosianus Matheron = Chlamys faujasi (Defrance). Derivatio nominis
For Henry WOODS. The trivial name has been formed on this famous palaeontologist's first name, because twice already a «Pecten» woodsi has been erected (5). Location of type-specimen
Sedgwick Museum, Cambridge (ColI. Meijer).
Stratum typicum
Cenomanian. Locus typicus
Wilmington, Devon (G. B.) Description
Number of specimens studied : total 28.
British Cenomanian ... ... ... ... ... ... 26 Belgian Cenomanian ... ... ... ... ... ... 1 French Cenomanian ... ... ... ... ... ... 1 Measurements:
U. P. D. vanes from 29.9 mm to 38.7 mm (n = 7) W. vanes from 24.4 mm to 33.5 mm (n = 6) A. A. vanes from 75° to 90° (n = 8) Ribnumber vanes from (24, 27) 32 to 42 (n = 7) Diagnosis.— Medium-sized Mimachlamys-species, relatively flattened, covered with numerous smooth ribs separated by narrow grooves.
To WOODS's description nothing significant can be added. Discussion
As stated under Chlamys faujasi DEFRANCE, Pecten puzosianus MATHERON belongs to that species. The confusion which started with A. J. JUKES-BROWNE has been occasioned by D'ORBIGNY's poor figure, which is indeed similar to the British specimens. However, D'ORBIGNY's description is similar to MATHERON's, and the specimens agree with the description and not with the figure. Hence A. J. JUKES-BROWNE and W. HILL, and H. WOODS figured and described a species which has never been named.
The species under discussion is closely related to Mimachlamys robinaldina (D'ORBIGNY). The disc shape is identical and as far as the ornamentation is concerned, pI. 30, fig. 12, in WOODS, 1902, is very close to a typical M. robinaldina ornamentation. It could be that Pecten rothomagensis D'ORBIGNY, which has been tentatively placed with M. robinaldina, has an ornamentation which is close to that described for M. henrici. At present it is impossible to decide whether the differences between M. robinaldina and M. henrici are of specific or subspecific level. M. henrici is restricted to the Anglo-Parisian Basin. Variability:
As in most Mimachlamys-species the ribnumber is extremely variable. Unfortunately the number of specimens on which the ribs could be counted is small and does not give an idea of the complete variability in the species. Differentiation:
See under M. robinaldina. Generic attribution:
On the small number of specimens known of Pecten puzosianus JUKES-BROWNE and HILL non MATHERON no characteristics are present which are non-Mimachlamys-characteristics. Pecten robinaldinus D'ORBIGNY which is very closely related to the species under discussion certainly belongs to Mimachlamys. Hence I consider that Pecten puzosianus JUKES-BROWNE and HILL non MATHERON should bear the new name Mimachlamys henrici. Stratigraphical and geographical distribution
Restricted to the Cenomanian of the Anglo-Parisian Basin.
BELGIUM: Montignies-sur-Roc (Mus. Gen.) FRANCE: Rouen, Seine-Maritime (KO.) GREAT BRITAIN: Beer Head, Devon (5. M.) N. of Beer Head, Devon (S. M. also orig. H. WOODS, B 199, pI. 30, fig. 9) Blue Bell Hill, Burham, Kent (B. M.) Brighton, Sussex (B. M.) Charmouth, Dorset (B. M.) Culver Cliff, Isle of Wight (ColI. C. JEANS) Dunscombe, Devon (5. M.) Hooken Cliff, Beer, Devon (B. M.) Melbury, Dorset (5. M. orig. WOODS, B 6211-6212, pI. 30, fig. 12) Pinhay, Devon (B. M.) Whitecliff, Devon (B. M.) Wilmington, Devon (B. M., S. M.)» (5) Pecten (Neithea) woodsi in J. WOLDRICH, 1918, p. 285, pI. 4, fig. 13 and Camptonectes woodsi G. TAVANI, 1940, p. 50, pI. 1, fig. 3.
ANNIE VALÉRIE DHONDT, 1973
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«Description. Medium-sized species distingushed from other representatives of the genus by its relatively flattened shell covered with numerous smooth ribs that are separated by narrow grooves.
Remarks. The number of ribs is very variable. It is possible that M. henrici may only be a subspecies of M. robinaldina. Occurrence. Cenomanian; mainly Devon and Dorset, but also found in Kent, Sussex and the Isle of Wight.» CLEEVELY, R. J. & N. J. MORRIS. 2002. Introduction to molluscs and bivalves. In A. B. Smith & D. J. Batten (Eds.): Fossils of the Chalk, 99-160. The Paleontological Association. London. [p. 121]
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Mimachlamys henrici Dhondt; R. J. Cleevely & N. J. Morris, 2002, Introduction to molluscs and bivalves, plate 20, figure 12.
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