Spondylus baileyana Chapman, 1922
CHAPMAN, F. 1922. New or little-known fossils in the National Museum. Part XXVI -some Tertiary Mollusca. Proceedings of the Royal Society of Victoria [New Series], 35 (1): 1-18, pls. 1-3. [p. 7, pl. 2, fig. 11]
1922 Spondylus baileyana Chapman, 1922
F. Chapman, 1922, plate 2.
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«Description.— Valves roundly to obliquely ovate; left valve depressed, right valve moderately convex. Shell thinner than in S. gaederopoides, McCoy. Hinge-line moderately long for the genus. Anterior margin of the shell widely rounded, curving obliquely to the ventral margin, and broadly rounded at the posterior angle. Surface of shell ornamented with about 6 principal radii, which are more than usually adpressed to the shell, but at intervals projecting into sharp spines, more strongly developed towards the posterior extremity. Smaller and almost obsolete radii between the stronger ones. Growth-lines faint except towards the ventral margin of full-grown specimens; never developing further than as a series of depressed lamellae. Inner surface with the margin finely toothed. Muscle impression large, situated close to the umbo.
Dimensions.— Type specimen, left valve. Length, 74 mm.; height, 82 mm. Observations.— This species is clearly the ancestral form of the living S. tenellus. Reeve,¹¹ which is found off New South Wales and Victoria (Western Port, Phillip Island and Portland). The fossil specimen is fully twice the height, with more widely spaced radii and stronger and more adpressed spines. The Kalimnan Spondylus spondyliolcides (or arenicola), Tate sp.,¹² from the Upper beds at the Murray Cliffs is distinguished by the more triangular shape and more spinous character, with obliteration of the concentric lamellae. Occurrence.— In calcareous shelly marl, Beaumaris, Port Phillip. Collected by the late J. A. Bailey, after whom the species is named. Also in the Dennant collection, from Rose Hill, near Bairnsdale, and from McDonald's, Muddy Creek (F.C.). Age.— Kalimnan (Lower Pliocene).» 11. Reeve, Conch. Icon., vol. ix., pl. xviii., fig 67.
12. Trans Roy. Soc., S. Australia, vol. viii., 1886, p. 19, pi. iv., fig. 6, as Pecten spondyloides. Renamed by Tate, 1896, in Rep. Australasian Association for the Advancement of Science, vol. vi., p. 318 as Spondylus arenicola. Although inappropriate, this earlier trivial name must stand, according to the rules of nomenclature. FREDERICK CHAPMAN, 1922
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