i)ii'[.()noN 1301 



neither full nor high, with subradial, curved bars, which draw 

 towards each other below ; posterior ridge full, rounded, end- 

 ing in a point below the median line ; dorsal and ventral lines 

 lightly curved or nearly straight, the latter often full behind 

 the middle ; anterior end slightly narrowed, rounded ; dorsal 

 slope obliquely truncate ; surface with fine, concentric sculp- 

 ture, sometimes with feeble, radial markings in front ; epider- 

 mis greenish-brown ; pseudocardinals compressed, disposed 

 often to be double in each valve : nacre bluish, thicker in front. 



Length 59, height 29. diam. 19 mm. 



Australia. 

 f Unio deprcssa I.amarck, An. sans. Vert., VI, 1819, p. 79. — 



? Dki.sssert, Rec. Coq. Lam., 1841, pi. xii, fig. 5. — Chenu, 



111. Conch.. 1858, pi. XII, figs. 4, 40. 

 Unio dehressHs Conrad, Jl. Ac. N. Sci. Phila., 1854, p. 295, pi. 



xxxvi, fig. 2. 

 Unio cultcUiformis Conrad. Pr. Ac. N. Sci. Phila., V, 1850, 



p. 10. 

 Margaron (Unio) cultcUiformis Lea, Syn., 1852, p. 32; 1870, 



P- 52- 

 Diplodon cultcUiformis Simpson, Syn., 1900, p. 802. 

 Unio paramattcnsis Lea, Pr. Ac. N. Sci. Phila., \l, 1862. p. 



176; Jl. Ac. N. Sci. Phila., VL 1866, p. 60, pi. xx, fig. 59; 



Obs., XT, 1867, P- 64, pi. XX, fig. 59. 

 Margaron (Unio) Paramattcnsis Lea, Syn., 1870, p. 35. 



Conrad's description of Unio cultelliformis agrees exactly 

 with Lea's U. paramattcnsis, numerous authentic specimens of 

 which are before me. 



I cannot identify Lamarck's Unio depressus with any cer- 

 tainty from his very meager description. As the name de- 

 pressus was used for a Unio in 1801 by Donovan I am obliged 

 to use another for this. 



Diplodon lutulentus (Gould). 



Shell elongated, subrhoniboid, compressed, quite inequilater- 

 al, sometimes slightly falcate, subsolid ; beaks low: posterior 

 ridge low, widely rounded ; anterior end slightly narrower than 



