106 



Eif^ht valve nearly ilat, depressed at the umbo ; ears equal 

 truncate, finely striated perpendicularly, faintly rayed. 



Dimensions. — Length, 47 ; height, 45 ; thickness through 

 both valves, 10 millimetres. 



Localities. — Common in the calciferous sandstone of the 

 Middle Murravian, Blanchetown, &c. ; rare in the Lower 

 Murravian at Mannum. Not uncommon at Muddy Creek, 

 Hamilton. 



This species belongs to a small group represented by 

 JP. Solaris, Born, but it is not identical with any of the living 

 species monographed by Reeve. P. solarium, Lamk., a fossil 

 species of the European Tertiary, is also of the same type, but 

 -P. Murrayanus is distinguished by its fewer ribs and smaller 

 wings. 



P. leopardus, Reeve, is its nearest ally, but the ribs are 

 fewer, separated by wide interspaces, and is scarcely equivalve. 



Pecten dichotomalis, spec. noi\ Plate ix., figs 3a— 3c. 



Shell suborbicular, fan-shaped, thin, equilateral, inequivalve^ 

 umbos depressed. Right valve regularly slightly convex, with 

 about nine broad radial undulose folds, whole surface orna- 

 mented with flat riblets narrower than the interspaces which 

 are crossed by raised threads about half the width of the alter- 

 nating grooves. The riblets increase in number to more than 

 100 by two successive bifurcations at irregular intervals, and 

 towards the margin are covered with minute imbricating scales ; 

 front margin undulate and minutely crenulated. Ears un- 

 equal, dorsal line distantly serrately fringed ; anterior ear 

 slightly sinuated on the underside, with five to six radial ridges 

 covered with small triangular serratures ; posterior ear trian- 

 gular, slightly obtuse-angled, with seven to eight serrated 

 ridges. Left valve flat, with the radial folds angular, the rib- 

 lets stouter and less numerous, the anterior one-fourth of the 

 surface densely covered with conspicuously large, erect scales. 

 Ears large, equal : radial ridges about three on which are a 

 few scattered, erect, triangular scales. 



Dimensions. — Length, 32 ; height, 30 ; thickness through 

 both valves, 4'5 millimetres. 



Locality. — Schnapper Point, Hobson's Bay (P. T.). 



Pecten antiaustralis, spec. nov. PI. ix., figs. 7a— 7c. 



Synonym. — P. asperrimus, var. Tate. Trans. Rov. Soc, S. 

 Aust., vol. iv., p. 34, 1882. 



Shell sub-orbicular, moderately convex sub-equivalve, the 

 right valve less convex, sub-equilateral, rayed with about 25 

 ribs which are flanked by one or two smaller ribs on each ; 

 the ribs and riblets are convex, crossed by erect lamellae, the 



