Terthn/.l PAL.F.ONTOLOGY OF VICTORIA. [Mollusca. 



Plate XXX., Figs. 1-lc. 



CYPR.^A (ARICIA) PLATYPYGA (McCoy). 



[Genus CYPE^EA (Lin.). (Sub-kingd. Mollusca. Class Gasteropoda. Order Pectinibran- 

 chiata. Fam. Cyprseidas.) 



Gen. Char. — Shell ovato-oblong ; spire very short, or entirely covered by the body whorl ; 

 back rounded ; inner and outer lips inrolled ; aperture narrow, as long as the shell, reflected at 

 both ends, transversely toothed and ridged on each side. 



Siib-yenus. — Aricia (Gray). Surface highly polished ; gibbous above ; flattened, thickened, 

 and dilated at the sides below ; spire covered ; aperture straight, narrow, outer and inner lips 

 callous, thickened, wide, dentated.] 



Description. — Siib-pyriform, g-lobose ; back nearly semicircular in longitudinal 

 profile, the posterior end being' more abruptlj' arched than the anterior portion, which 

 forms nearly quarter of a circle, from wliicli the narrow sub-cylindrical slightly 

 retiexed anterior canal extends abruptly, nearly at right angles, flanked on each side 

 by a thickened extension of the base ; posteiior canal short, extremely wide, extended 

 chiefly on the right hand side, undulato-truncate behind ; spire visible, of 2-i narrow 

 convex turns ; base moderately thickened ; outer lip inflected, rounded, the whole 

 length set with coarse, strong, sub-equal teeth extending- from 3 to 4 lines laterally 

 as strong rounded ridges ; inner lip with a broad flattened space sloping- inward, 

 very coarsely sulcated throughout by sub-equal, broad, flattened, prominent ridges, 

 separated b}' narrow sulci, about G lines long-. Length, 3 inches i lines ; proportional 

 width, .j^^; depth, y^jj^j ; length of anterior canal, y^,-^ ; width of anterior canal, about 

 -p'^% ; length of posterior canal, J,/^ ; width of posterior canal, J^^jj ; diameter of 

 exposed spire, -j'/j. 



In the form of the base, the strong dental sulcation of the lips, 

 and in the size of the exposed whorls of the spire, this species 

 approaches C. exwiia, but is much shorter and more gibbous, has 

 much shorter anterior canal without tubercles, and it differs from 

 it and all other species most remarkably in the great width of the 

 subtruncate posterior end, indicated by the specific name. 



Very rare in the Oligocene Tertiary clays of shore near foot of 

 Movmt Eliza. 



Explanation op Figures. 



Plate XXX. — Fig. 1, longitudinal profile, natural size. Fig. la, dorsal view of same speci- 

 men, showing the narrow cylindrical anterior canal, the wide truncated posterior end, and 

 the partially exposed spire. Fig. 16, posterior end view of same specimen, showing rounded 

 transverse outline, and partially exposed spire. Fig. Ic, under view of same specimen, showing 

 thickened rounded base, with narrow mouth, strong teeth of outer lip, and coarse sulcation of 

 inner lip. 



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