Tertiary. | PALZONTOLOGY OF VICTORIA. (Mollusca. 
or right valve, being marked by sudden irregularity of general 
growth and change of the character of the ridging, and by the 
development on the lower or right valve of the large concentric 
irregular shelly fringes like those of Spondylus. 
Extremely common in Miocene Tertiary of Corio Bay ; and in 
similar beds near Bairnsdale, on the Nicholson River. 
EXPLANATION OF FIGURES. 
Plate LVIII.—Fig. 1, average specimen of left valve, natural size. Fig. la, magnified view 
of striation, showing the proportions of the interspaces and the character of the vaulted scales 
forming the tuberculation about the middle of the shell on the older stage of growth. Fig. 14, 
magnified view, showing character of more uniform ridges with blunt tubercles becoming 
obsolete near margin of old specimen. Fig. 2, magnified view of another specimen, showing the 
ridging of the ears. Fig. 3, view of right valve, natural size, showing the regular character 
of the byssiferous early stage of growth near the beak and the distorted transversely squamous 
older stage of growth nearer to the margin. Fig. 4, another specimen of right valve, natural 
size, viewed in profile, showing the great depth sometimes attained, the regular Pecten-like 
early growth near beak, beyond which is the large scar produced by the subsequent calcareous 
attachment, beyond which the concentric scale-like shelly fringes as in Spondylus are seen and 
the nearly equal ridges. 
Freperick McCoy. 
