NO. 1205. SYNOPSIS OF THE NAIADjES—SIMPSOX. 849 



PARREYSIA HYPSIPRIMNUS von Martens. 



* Unto hypsijjrimnus voN Martens, Besch. Deuts. Ost-Af., 1897, p. 230, pi. vii, 

 fig. 1.1 



Lake Nyassa. 



(Group of Parreysia moUeuri.) 



Shell subquadrate, solid, intlated, rounded iu front, truncated behind, 

 with high beaks, the sculpture of which was not observed, and a strong-, 

 sharp, curved posterior ridge; surface concentrically grooved; pseudo- 

 cardinals thick, short, cut up with vertical grooves; laterals curved; 

 nacre white. 



PARREYSIA MOLLEURI Morlet. 

 *Unio moUeuri Morlet, Jl. de Conch., XXXIX, 1891, p. 242, pi. vii, fig. 4. 



Valley of the Mekong Eiver. 



Subgenus ATJEOEA Simpson, 1900. 



(Type, Unio aurorens Heude.) 



Shell small, ovate, subinflated, pointed behind, rather solid, with 

 high, small beaks and strong, corrugated sculpture, which exiends over 

 half the disk iu somewhat lachrymous, zigzag ridges and nodules, the 

 outer part of the disk apparently having one or more strong, concen- 

 tric ridges, the posterior slope being radiately ridged and nodulous; 

 epidermis fulvous, beautifully and delicately green radiated; pseudo- 

 cardinals conical, truncate, striate ; laterals lamellar; nacre orange.^ 



PARREYSIA AUROREA Heude. 



^ Unio aurorens Heude, Conch. Fluv. Nank., VIII, 1883, pi. lvii, fig. 106.— 

 *P^TEL, Conch. Sam., Ill, 1890, p. 145. 



China. 



Subgenus PSEUDOBAPHIA Simpson, 1900. 

 (Type, Unio hiesianus Heude.) 



Shell large, oval, inflated, gaping in front and behind, rather solid, 

 with full beaks, the beak sculpture not seen, posterior part distinctly 

 biangular; ligament large; epidermis smooth, brownish, somewhat 

 rayed, right valve with a large, irregular pseudocardinal in front of the 

 beak, with a pit in front of it: behind it on the hinge are numerous 

 denticles, and at some distance behind two very faint 1 at eials; left valve 

 with two large pseudocardinals, one behind the other, and two remote 



II am not positive as to the systematic position of this and the last two species. The 

 figure of the latter is from a very badly eroded shell, aud it is difficult to tell what its 

 affinities are. 



■Heude's brief Latin description so poorly describes the peculiar species placed 

 here that I can not be sure where it belongs, aud that it should not have generic 

 rank. I j)lace it here provisionally. 



Proc. N. M, vol. xxii 54 



