Ill 



*' This fossil resembles the well-known German Miocene 

 Tertiary species, the Pecten Hofmanni of Goldfuss, so nearly 

 that at first sight one might mistake one for the other ; the 

 Tidges, however, are slightly larger, nsually more nearly equal 

 and less rigid in this species, which is totally distinguished by 

 having the right or deeper valve different from the other, while 

 .they are both alike in the P. Hofmanni " {ILcCoy, op. cit.). 



Pecten Foulcheri, Tenison Woods. 



Pecten sp., Sturt. Two Exped., &c., tab. 3., fig. 1-1. 



Pecten sp., Tenison AVoods, Geol. Observ., p. 74 (1862). 



P. Foulcheri, Tenison AVoods, Proc. Phil. Soc. Adelaide, 1865, 

 .tab. 1, fig. 3. 



Shell thin, equivalve, inequilateral by projection of the front ; 

 valves flatly convex with about nine radial angular plicae on 

 which are scattered towards the front spinous imbrications 

 passing to squamose imbrications on the umbonal region, the 

 -concave furrows and sides of plicae with about nine raised lines, 

 squamosely imbricate especially towards the umbo, the whole 

 crossed by fine concentric striae. 



Ears very unequal ; the left anterior moderately large trian- 

 gular ornamented with three to four rays, squamosely imbri- 

 cated towards proximal end, and concentric stria?, l^ef t posterior 

 large aliiform with a deep byssal sinus, ornamented with five 

 ■or six squamosely-imbricate rays. Right anterior as left an- 

 terior, llight posterior much larger, subaliiform with several 

 scaly rays. 



Dimensions of an averaged speciaien. — Length 33, thickness 

 34, thicknes through both valves millimetres. A large 

 specimen measures 41 by 43 millimetres. 



Localities. — Somewhat common in the Mount Gambier lime- 

 stone (Tenison Woods) ; very abundant in the Calciferous sand- 

 stone of the Elver Murray Cliffs (P. Tate) ; Table Cape, 

 Tasmania (B. M. Johnston !) ; rare Muddy Creek. 



Tenison Woods' illustration of this species is a good repre- 

 sentation of the common form, around which may be grouped 

 several varieties ; whilst individual variations have been de- 

 veloped to such extremes that it would be justifiable to estab- 

 lish three or four species out of them if the connecting varia- 

 tions were awanting. 



In the typical form the spinous-processes on the plicae are 

 slender and distant, occasional examples show crowded large 

 imbricating squamae and the ornament on the interstitial ridges 

 •equally gross. Again the plicae are broad and convex ; in 

 others the flanking ridges to the plicae acquire the magnitude 

 •of the central ridge, this state is usually accompanied by almost 

 obliteration of the furrows and the substitution of scales for 

 spines. 



