340 PROCEEDINGS OF THE NATIONAL MUSEUM. 



fPSEUDODON SECUNDUS Heude. 



* Pseudodon secundns Heude, Conch. Fluv. Nauk., Ill, 1877, pi. xviii, fig. 38. 

 Unio secundns Ptetel, Conch. Sam., Ill, 1890, p. 167. 



Eiver Hoie, China. 



Section OBOVALIS Simpson, 1900, 

 (Type, Pseudodon loomisi Simpson.) 



Shell obovate subinflated, with a low, rounded posterior ridge, and 

 with radiating- wrinkles on the posterior slope; disk nearly free from 

 wrinkles; epidermis blackish; there is a high, triangular tooth in each 

 valve; laterals very faint, rounded; nacre coppery. 



Animal unknown. 



I PSEUDODON LOOMISI Simpson. 



* Pseudodoti loomisi Simpson, Pr. Ac. N. Sci. Phila., 1900, p. 84, pi. iv, fig. 7. 



Japan. 



The following are unfigured or indeterminate species. 



Monocondyloea walpolei Hanley, Proc. Zool. Soc. Loud., 1871, p. 587. Borneo. 



Spatha compressa von Maeteits, Proc. Zool. Soc. Lond., 1860, p. 66. Siam. 



Pseudodon sulcatum Eochebrune, Bull. Soc. Phil., 7th ser., VI, 1882, p. 41. Me- 

 kong River, Cochin China. 



Pseudodon pierri Rochebrune, Bull. Soc. Phil'., VI, 1882, p. 41. Cochin China. 



Pseudodon maUllei Rochebrune, Bull. Soc. Phil., VI, 1882, p. 41. Cochin China, 

 Cambodia. 



Pseudodon anodontinus Eochebrune, Bull. Soc. Phil., VI, 1882, p. 41. Cambodia. 



Genus PARREYSIA Conrad, 1853. 

 (Type, Unio multidentatus Philippi.) 

 Parreysia Conrad, Pr. Ac. N. Sci. Phila., VI, 1853, p. 267. ^ 



Shell solid, inflated, oval to subrhomboid, with full, high, zigzag, 

 radially sculptured beaks, the sculpture often extending over the disk; 

 epidermis smooth and bright, sometimes a little rayed, with two irreg- 

 ular pseudocardinals in the left valve which are more or less broken 

 into ragged denticles or are strongly, vertically striate, and two later- 

 als, the lower the larger; right valve with one, sometimes two pseudo- 

 cardinals, the upper small, compressed, and a few tubercles behind 

 them, with two laterals, the upper the larger; cavity of the beaks 

 rather deep, not compressed; dorsal scars under the hinge, not visible; 

 the two upper anterior muscle scars very deep, confluent, the lower 

 linear ; nacre white to salmon, iridescent behind. 



Animal unknown. 



Subgenus PAEREYSIA Conrad, 1853= 



Characters the same as the genus. 



1 In the above reference Conrad gives the name Parreysia and refers to Unio multi- 

 dentatus Parreyss, which may be taken as the type. I do not know that he ever 

 described the group. 



