so. 1205. SYNOPSIS OF THE NAIADES SIMPSOS. 847 



PARREYSIA MULTICOLOR von Martens. 



* Unio multicolor vox MAKTKNS, Resell. Dents. Ost-Af., 1897, p. 236, pi. vn. fig. 4. 



Lake Victoria Nyanza. 



PARREYSIA NGESIANUS von Martens. 



* Unio nyesianus VON MARTENS, Beach. Dents. Ost-Af., 1897, p. 234, pi. vn. fig. 7. 



Lake Albert Edward Nyanza. 



Tbe following unfigured species are placed iu this group bv vou 

 Martens : 



Unio Mllotiantts CHAR.MKS, Bull. Soc. Mai. Fr., II, 1885, p. 170. Bagamoyo, Central 



Africa. 



Unio euphymus CHARMES, Bull. Soc. Mai. Fr., II, 1885, p. 171, Baganioyo. 

 Unio dumesleanus CHARMES, Bull. Soc. Mai. Fr., II, 1885, p. 168, Baganioyo. 



(Group of Parreysia fabagina.) 



Shell very small and solid, inflated, compressed ou the sides, rhomboid, 

 with a high, sharp posterior ridge and high beaks, having zigzag-radial 

 sculpture sometimes extended over the disk, the posterior slope fur- 

 nished with upcurved plications; pseudocardinals heavy, torn, one in 

 the right valve, two in the left; muscular impressions circular, the 

 anterior very deep. 



PARREYSIA FABAGINA Deshayes. 



* Unio fabagina DESHAYES, Nouv. Arch, de Mus., X, 1874, p. 128, pi. vn, figs. 4-6. 



*P,TEL, Conch. Sam., Ill, 1890, p. 152. * FISCHER, Bull. Soc. d'Hist. Nat. 

 Autnn., 1891, p. 140. 



Mekong River, Cambodia. 



PARREYSIA BROTI Deshayes. 



* Unio broti DESHAYES, Nouv. Arch, de Mus., X, 1874, p. 129, pi. vu, figs. 1-3. 



* CROSSE and FISCHER, Jl. de Conch., XXVI, p. 323. *PJETEL, Conch. Sam., 

 Ill, 1890, p. 146. 



Mekong River, Cambodia. 



(Group of Parreysia nyassaensis.) 



Shell small, solid, inflated, triangular to rhomboid, the base straight 

 or even a little arcuate, but sometimes having a slight fullness behind 

 the central part; a high, well-defined posterior ridge ends at the post 

 base and is sometimes slightly double; posterior slope abrupt; beaks 

 high, with zigzag-radial sculpture, the bars approaching and often 

 coalescing behind the center of the disk, the whole shell frequently 

 corrugate sculptured ; epidermis greenish, often slightly rayed; teeth 

 solid, much like those of typical Parreysia; nacre white or bluish, 

 sometimes microscopically, granularly radiate outside the palleal line; 

 beak cavities not deep; anterior scars distinct. 



Animal unknown. 



