1306 DIPI,ODON 



from nodules. The line of juncture between the noduled and 

 non-nodulous area runs obli(|uel\ nearly parallel with the 

 posterior rid.i^e. 



Group of Diplodon slutttlcwortlui. 



Beak sculpture consisting- of strong, irregularly radiate, 

 curved, nodulous bars ; surface of shell somewhat sulcate, but 

 not nodulous. 



Dii'i.ono.v siii'TTi.t;\vt)R'i'Hir (Lea). 



Shell much elongated, rather solid, scarcely subinflated, sub- 

 rhomboid, inequilateral : beaks low, subcompressed, sculptured 

 with radial bars, which curve towards each other; posterior 

 ridge elevated, rounded above, sometimes more or less double 

 below ; dorsal line slightly curved ; base line nearly straight ; 

 anterior end narrowed, rounded, often cut away below ; dor- 

 sal slope obliquely truncated ; lower part of dorsal end round- 

 ed or feebly biangulate ; surface with rather strong, concen- 

 tric sculpture ; posterior part of the shell covered with strong, 

 subradial, more or less nodulous, ribs ; epidermis thick, black- 

 ish, rather dull; pseudocardinals weak, often smooth and al- 

 most obsolete in old shells ; laterals remote, single and ele- 

 vated in the right valve, double and feeble in the left ; dorsal 

 scars distinct ; anterior scars double, impressed ; posterior scars 

 elongated ; pallial line crenated ; nacre bluish to lurid purplish, 

 thicker in front. 



Length 132, height 51, diam. 31 mm. 



Australia. 

 Unio shuttleivorthii Le.\. Pr. .\c. N. Sci. Phila.. VIH, 1856, 



p. 94 ; J1. Ac. N. .Sci. Phila., Ill, 1857, p. 304, pi. xxviii, fig. 



19 ; V'L 1857, p. 24, pi. xxviii, fig. 19. — Sow^ERBY, Conch. 



Icon., XV'L 1866, pi. xxxiT, fig. 167. 

 Margaron fUnio) shnttleworthii Lka, Syn.. 1870, p. 36. 

 Diplodon shuttleii'orthn vSimpson, Syn., 1900, p. 893. 

 ? Unio miitaJ'ilis Rrfa'!;, Conch. Icon.. X\l, 1865, pi. xxiv, fig. 



112. 



