Ko. 1205. SYNOPSIS OF THE NAIADES— SIMPSOX. 847 



PARREYSIA MULTICOLOR von Martens. 

 ** Unio multicolor YON Martens, Bescli. Deuts. Ost-Af., 1897, p. 236, pi. vii. fig. 4. 



Lake Victoria Nyauza. 



PARREYSIA NGESIANUS von Martens. 

 " Unio ngesianus von Martens, Besch. Deuts. Ost-Af., 1897, p. 234, pi. vii. fig. 7. 



Lake Albert Edward Nyanza. 



Tbe following unfigured species are placed in this group bv von 

 Martens : 



Vnio Mllotianiis Charmes, Bull. Soc. Mai. Fr., II, 188.5, p. 170, Bagamoyo, Ceutral 



Africa. 

 Unio euphymus Charmes, Bull. Soc. Mai. Fr., II, 1885, p. 171, Bagamoyo. 

 Unio dumesleanus Charmes, Bull. Soc. Mai. Fr., II, 1885, p. 168, Bagamoyo. 



(Group of Parreysia fahagina.) 



Shell very small and solid, inflated, compressed on tbe sides, rhomboid, 

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

 sculpture sometimes extended over the disk, the posterior s\o])e fur- 

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

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

 anterior very deep. 



PARREYSIA FABAGINA Deshayes. 



* Unio fahagina Deshayes, Nouv. Arch, cle Mus., X, 1874, p. 128, pi. vii, figs. 4-6. — 



*P/ETEL, Couch. Sam., Ill, 1890, p. 152.— * Fischer, Bull. Soc. d'Hist. Nat. 

 Autun., 1891, p. 140. 



Mekong River, Cambodia. 



PARREYSIA BROTI Deshayes. 



* Unio hroti Deshayes, Nouv. Arch, de Mus., X, 1874, j). 129, pi. vii, figs. 1-3. — 



* Crosse and Fischer, Jl. de Conch., XXVI, p. 323. — *P^tel, Couch. Sam., 

 Ill, 1890, p. 146. 



Mekong Eiver, 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 ceutral part; a high, well-defined posterior ridge ends at the post 

 base and is sometimes slightly double; posterior sloj)e 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 sears distinct. 



Animal unknown. 



