316 



in the adult ; tlie costse are convex, crossed by erect lamellse, the 

 furrows being flattened and transversely striated ; auriculse very 

 unequal in size, the large projection on one side of the umbo being 

 well-marked by fine costae. 



Dmensions. — Height 59 mm. ; length 56"5 mm. 



Form, and Loc. — Miocene : South Australia and Victoria. 



33789. Example of the neanic stage of growth ; (locality ?) 

 South Australia. Presented by J. B' Urban, Esq. 



42698. Three specimens ; from near Adelaide. 



Presented by M. Marshall, Esq. 



L. 6679, L. 9918. Series illustrating stages of growth, both 

 valves ; from Muddy Creek. Purchased. 



L. 10533. Examples of the ephebic and neanic stages; from 

 Willunga. S. T. L. Brown Coll. 



Pecten polymorphoides, Zittel. 



1833. Pecten coarciattis, Sturt, Two Expeditions S. Aust. vol. ii. p. 254, 



pi. iii. fig. 13. 

 1862. Fecten coarctalus (?), J. E. Woods, Geol. Obs. S. Aust. p. 74, fig. 

 18b5. Pecten polymorphoides, Zittel, Eeise der Novara, Palaontologie, Bd. i. 



Abth. ii. p. 61, taf. si. fig. 3. 

 1865. Pecten incertus, Tenison-'Woods, Trans. Phil. Soc. Adelaide, pi. i. 



fig. 1. 

 1886. Pecten polymorphoides, Tate, Trans. Koy. Soc. South Aust. vol. viii. 



p. 113, pi. viii. fig. 2. 

 1889. Pecten polymorphoides, Dennant, id. vol. xi. p. 49. 

 1893. Pecten polymorphoides, Tate and Dennant, id. vol. xvii. pt. 1, p. 224. 



Shell inequivalve, very inequilateral, irregularly convex, typically 

 bent inwards along the ventral margin ; ornamented by from five 

 to seven broad undulating costse, which, together with the inter- 

 spaces, bear numerous minor radiating riblets; ridges commonly 

 covered with imbricating scales ; auriculaj very unequal in size, the 

 smaller one is grooved in front from the umbo, and that leads 

 to a general lateral inflection, which is highly characteristic, 

 producing a distorted appearance in the shell. It is an exceedingly 

 variable species. The synonymy is fully discussed by Professor 

 Tate {op. cit. 1886, p. 113). 



Dimensions. — Height 36 mm. ; length 37'5 mm. 



Form, and Loc. — Eocene : Victoria. 



