I 142 I'ARKl'.^'SIA 



Nacre very shining. Anterior muscular impressions round, 

 posterior elongated, rather faint. Hinge very weak. In the 

 right valve, two, weak, elongated cardinals and a single lat- 

 eral equally weak and elongated. In the left valve one cardinal 

 and two laterals. 



Epidermis hluish-green with metallic reflections, ornament- 

 ed with concentric zones and rays of yellow. Nacre very iri- 

 descent. 



Length zj, height 16, diam. 11 mm." (Dautzenberg). 



Type locality, Bay of Kavirondo, Victoria-Nyanza. 

 .{Jnio (Parreyssia) allnaudi Dautzenberg, Jl. de Conch., LVI, 



1908, p. 26, pi. II, figs. 13, 14, 15, 16. 



■"Although a certain number of species of Unio are known 

 from Lake Victoria, we have not been able to refer to any one 

 of them, the one here described. It is characterized by its thin, 

 very brilliant shell with metallic reflections, weak hinge, elon- 

 gate form, attenuate and rostrate at the posterior end and by 

 the convex, ventral margin, projecting in the middle. 



The sculpture is very variable in Unio alluaudi: sometimes 

 the zigzag folds appear only in the umbonal region ; but they 

 frequently extend over the whole surface. The coloration is 

 equally variable, for we have seen examples without rays and 

 of a uniform yellow." 



Pareyssia mweruensis (E. a. Smith). 



"Shell small, inequilateral, moderately thin, narrowly gap- 

 ing at both ends, rounded in front, narrower and produced 

 posteriorly, covered with a brownish-olive periostracum, some- 

 times painted posteriorly with radiating green lines, smooth 

 but sculptured with lines of growth and more or less corru- 

 gated towards the umbones ; umbones eroded, placed well for- 

 ward ; nacre white, pearly, iridescent ; cardinal teeth rugose, 

 laterals thin, elongated ; anterior cicatrix moderately deep, 

 posterior light, not impressed. 



Length 26, height 15, diam. 10.5 mm." (Smith). 



Type locality, Lake Mweru. 

 Unio mzvernensis E. A. Smith, Pr. Mai. Soc. London, ATIT, 



T908, p. 13, text- figs. 



