Tertiary. ] PALZONTOLOGY OF VICTORIA. [ Mollusca, 
no recent species very nearly allied to it ; the S. multimuricata of 
the Moluccas coming perhaps nearest, but having more numerous 
ridges with thicker and coarser spines, and much fewer and less 
spinulose intermediate strie. Of fossil species, the nearest is the 
S. rarispina (Desh.) and the S. radula (Desh.) of the older French 
Tertiaries, from which it differs in its narrower form, fewer large 
ribs, and more numerous and more spinulose interstitial ones. The 
concentric scaly lamine so common on the rostral portions of the 
lower valve of this genus are scarcely indicated, and only on the 
sides, if at all. The species is in most localities only about 13 
inches in length, but at Bairnsdale Mr. Howitt has collected gigantic 
specimens, upwarés of 3 inches in length, which agree with the 
others in all the main characters, and in these the unusual thinness 
of the valves is even more remarkable than in the small ones, 
recalling the living Australian Spondylus fragilis of Sowerby in 
this respect (although quite different in all other characters). Some 
of these Bairnsdale specimens show the spines nearly 14 inches in 
length, tapering to the end and with the remarkable lateral com- 
pression contrasting with the flattening in the opposite direction 
more common in other species. 
Not uncommon, of small size, in the Oligocene Tertiary clays and 
limestones near Mount Martha, in Port Phillip Bay ; rare, of small 
size, in the clay beds of Muddy Creek ; about the same size in the 
sandy Tertiary (A* 28) of Fyansford. 
Very large in the sands and limestones of Miocene Tertiary age 
of Bairnsdale. 
Of large size, very thin and fragile, in the Older Pliocene sandy 
clays of Mordialloc. 
EXPLANATION OF FIGURES. 
Prater XLV.—Fig. 2, upper valve of middle sized specimen, natural size. Fig. 2a, view of 
hinge of same specimen. Fig. 26, profile outline view of same specimen, Fig. 2c, portion of 
surface magnified to show the spinulose character of the smaller ridges between the larger ones. 
Frepertck McCoy. 
[ 18 ] 
