CASTALINA 1207 



Unio psammoica cI'Oreigny, Giier. Mag,. 1835, p. 35 ; Voy. 



Am. Mer., 1843, p. 608, pi. 1.XXI, figs. 4-7.— Kuster, Conch. 



Cab. Unio, 186 1, p. 263, pi. lxxxviii, fig. 4. 

 Castalma psammoica von Ihering, Arch, fiir Nat., 1893, p. 79. 



— Simpson, Syn., 1900, p. 866. 

 Margaron (Unio) psammoicus Lea, Syn., 1852, p. 19; 1870, 



p. 30. 

 Unio psammoicus Sowerby, Conch. Icon., XVI, 1868, pi. xciii, 



fig- 507- 



This species has been placed with Unio, but von Ihenng 

 correctly referred it to his new^ genus Castalinn. It is more 

 triangular than C. martensi. has stronger and more extended 

 beak sculpture, the surface is subdecussated, and the teeth are 

 not so strong, nor are they vertically striated. 



Castalina undosa (von Martens). 



Shell subtriangular, solid, slightly inflated, inequilateral; 

 beaks high and full, their sculpture feebly radial; posterior 

 ridge prominent, angled, often curved upward in the middle, 

 placed near the post-dorsal border, ending behind in a rounded 

 point near the shell's base; base line lightly curved; surface 

 rudely and irregularly, concentrically sculptured, the abrupt, 

 subtruncate dorsal slope covered with strong plications ; epider- 

 mis thick, blackish; pseudocardinals more or less spht up, 

 radial, and, with the laterals, vertically striate; beak cavities 

 deep : nacre bluish-white, not greatly thickened in front. 



Length 63, height 53. diam 30 mm. 



Southern Brazil. 

 Castalia undosa von Martens, S. B. Nat. Fr., 1885, p. 148; 



Conch. Mitth., Ill, 1885, p. 19, pi. xlii, figs. 2, 3. 

 Castalina undosa Simpson, Syn.. 1900, p. 866. 



This may be at once separated from the other allied species 

 by its strong folds running nearly across the dorsal slope. The 

 upper anterior region of the shell is sometimes corrugated. 



Group of Castalina orbignyi. 



Shell irregularly rhomboid, somewhat compressed, equilater- 

 al, anterior end rounded, posterior truncate, having a wide, 

 shallow, radiating furrow above the rounded posterior ridge, 



