142 



The Lamellibranchs of the Older Tertiary 

 of Australia. (Part II.) 



By Professor Ralph Tate, F.G.S., F.L.S., &c. 



[Read October 5, 1886.] 



Plates XIV., XV., XVI., XVII., XVIII., XIX, XX. 



FAMILY LUCINUXE. 

 Gexus LrciNA. 



SYNOPSIS OF SPECIES. 



a. Shell more or less inflated. 



Ornament of concentric lamellae or striae. 

 Lamellae thick. 



Quadrately orbicular. L. leucomomorpha. 



Obliquely ovate. L. projecta. 



Concentrically striated ; shell subglobose ; margin of 



valve plain. L. arcea. 



Margin of valves crenulated. L. ajflnis. 



Ornament of concentric lamellae and radial lines. 



Grlobose with thick lamellae. L. nuctformis. 



Quadrately orbicular, bifid incised radial lines. 



L. araneosa. 

 Obliquely ovate. L. despectans. 



Ornament of divaricate ridges. L. quadrisulcata. 



B. Shell compressed. 



Ornament of lamellar folds. L.fabuloides. 



Ornament of radial threads and concentric lamellae. 



L. planatella. 



Lucina leucomomorpha, Tate. 



Reference. — Tran. Roy. Soc, S. Aust, for 1885, t. xii, fig. 7. 



Shell quadrately orbicular, moderately convex, subequi- 

 lateral ; umbones email, incurved, contiguous, medial; slightly 

 excavated in front of the umbones, and slightly depressed in 

 the antero-dorsal region ; posterior margin truncated ; ventral 

 margin convex outwardly. Surface ornamented with numerous 

 regular concentric lamellae, which are slightly retroflexed at 

 the front. 



Lunule cordate, small, rather deep ; anterior lateral teeth 

 obscure ; right valve with one small cardinal tooth, left valve 

 with two cardinal teeth ; ligamental scar linear, submarginal ; 

 edge of valve obscurely crenulated. 



Dimensions. — Antero-posterior diameter, 11 ; umbo-ventral 



