I050 



HAUMANDIA 



truncate ; posterior ridge low, ending behind in a feeble bian- 

 giilation; surface sculptured with strong, irregular, subradial 

 ridges, which are heaviest on the middle of the disk ; epidermis 

 o-rayish-green ; anterior pseudocardinal of the left valve elon- 

 gated, convex, double; posterior subtriangular and connected 

 with the long straight laterals; right valve with two oblique, 

 lamellar pseudocardinals ; each valve with two long laterals 

 and an additional lamella branching and curving upward from 

 near their posterior ends ; nacre pearly, shining. 



Length 49, height 28, diam. 16 mm. 



Rapids of Sombor-Sombor, Mekong. 

 Harmmidia somboriensis Rochebrune, Bull. Soc. Phil., VI, 



1882, p. 46, pi. T, figs. 1-3. — Simpson, Syn., 1900, p. 827. — 



Haas, Conch. Cab., Unio, 1912, pi. 31, fig. 10. 



A remarkable shell with very strong, subradial sculpture, 

 the heavy ribs in front of and behind the beaks coalescing be- 

 low. The upper lateral in each valve bifurcates near its pos- 

 terior end, the small upper part curving away from the main 

 lateral. 



Harmandia castelneaui Rochebrune. 



"Shell compressed, subovate, solid, brownish-gray ; above 

 straight ; below obliquely convex ; anterior end short, nearly 

 straight, pointed, point obtuse, conic ; posterior end expanded 

 in a broad, thin, compressed wing ; surface radiating costate, 

 anterior ribs eight, straight, oblique, granular above ; posterior 

 ribs five, wide, curved, laminated, set at an angle with those 

 of the anterior region ; the interval between the ribs circularly 

 striate with heavy, undulating stride ; cardinal tooth in the 

 right valve oblique, jagged; in left valve subexcavated ; ante- 

 rior lateral very short, nearly straight ; median the longest, 

 subconcave, angulated ; posterior short, straight ; umbones 

 very short, eroded ; nacre of a bluish lead-color, very brilliant. 



Long. 52, lat. 32, crass. 12 mm." (Rochebrune). 



Type locality. Cochin China. 

 Harmandia castelneaiii Rochebrune, Bull. Mus. Hist. Nat., 



1904, p. 139. 



