NO. 1205. SYNOPSIS OF THE VATA DES SLUT'SO \. 885 



fDIPLODON PATAGONICUS d'Orbigny. 



* Unio patayonica D'ORBIGNY, Guer. Mag., 1835, p. 37; *Voy. Am. Mer., 1843, p. 



610, pi. LXX, figs. 1-4. 



* Margarita ( Unio) patagonicm LEA, Syn., 1838, p. 25. 



* Unio patagonicus HANLEY, Test. Moll., 1842, p. 208; * Biv. Shells, 1843, p. 208, 



pi. xxn, fig. 16. *CATLOW and REEVE, Conch. Norn., 1845, p. 62. *II. and 

 A. ADAMS, Gen. Rec. Moll., II, 1857, p. 461.* REEVE, Conch. Icon., XVI, 1865, 

 pi. xxi, fig. 93.* STROBEL, Mat. Mai., Pt. 1, 1874, p. 72.* P.ETEL, Conch. 

 Sam., Ill, 1890, p. 162. 



* Margaron ( Unio) patagonicus LEA, Syn., 1852, p. 38; 1870, p. 61. 



Patagonia. 



tDIPLODON ACUTIROSTRIS Lea. 



* Unio aculirostris LEA, Pr. Ac. N. Sci. Phila., X, 1866, p. 34; * Jl. Ac. N. Sci. 



Pbila., VF, 1868, p. 270, pi. xxxv, fig. 84; * Obs., XIII, 1869, p. 30, pi. xxxv, 

 fig. 84. 



* Margaron ( Unio) acutirostria LEA, Syn., 1870, p. 58. 



South America. 



(Group of Diplodon quadram.) 



Shell subtrapezoid, slightly truncate in front, nearly equilateral, 

 greatly inflated, its greatest diameter below the beaks, from which it 

 is wedge-shaped in front and behind, solid, with a decidedly rounded 

 posterior ridge; epidermis brownish, concentrically striate, beaks full 

 but not high, ligament long and slender; pseudocardinals large, com- 

 pressed, striate and creuulate, double in the right valve, single in the 

 left; laterals curved, crenulate; beak cavities rounded; anterior cica- 

 trices deep, confluent; nacre white. 



Animal unknown. 



DIPLODON QUADRANS Lea. 1 



*Unio quadrana LEA, Pr. Ac. N. Sci. Phila., IV, 1859, p. 306; *J1. Ac. N. Sci. 

 Phila., IV, 1860, p. 360, pi. LXI, fig. 185; * Obs., VIII, 1860, p. 42, pi. LXI, fig. 

 185.* B. H. WRIGHT, Check List, 1888. 



* Margaron ( Unio) quadrans LKA, Syn., 1870, p. 36. 



South America ( ?). 



Subgenus CYCLOMYA Simpson, 1900. 

 (Type, Unio fnnebr all* Lea.) 



Shell obovate to suborbicular, narrowed in front, produced just behind 

 the center of tbe base, generally slightly pointed about the middle of 

 tbe posterior end, with a scarcely perceptible posterior ridge and a 

 slight dorsal wing behind; beaks high, irregularly radial ; hinge line 



1 Only one specimen of this shell is reported, this being in the Wheatley collection, 

 and credited to Texas. The beak sculpture is all eroded away, but I am almost sure 

 it is a South American shell, allied, perhaps, to D. apprimua, uruguayensis, and possi- 

 bly to Hupe's Unio orbignyi. 



