186 MOLLUSCA OF THE THIRD TANGfANYIKA EXPEDITION. [Mar. 6, 



strongly spirally striated than other examples which have been 

 examined. 



5. Unio louedeli Bourguignat. 



Hah. Dredged in about a fathom in the harbour. 



6. CoRBicuLA cuNNiNGTONi, sp. n. (Plate X. fig. 15.) 



Shell small, irregularly ovate, almost equilateral, moderately 

 convex, sculptured with rather distinct and distant concentric 

 ridges, which become almost obsolete on both dorsal slopes ; valves 

 yellow olivaceous, with or without a few brownish rays, more oi' 

 less deep ptu^plish within; umbones prominent. Length 12^ 

 millim., diam. 8, height 11. 



Hah. Dredged in about a fathom in the harbour. 



This species may be sejDarated from C racliata Parreyss, the 

 only species recorded fi-om the Lake, on account of its somewhat 

 different form, the umbones being more prominent, the more 

 distant concentric ridges, and a difference in colour. None of the 

 specimens exhibit the characteristic dark purple ray proceeding 

 from the umbo down the middle of the valves as in C. radiata. 

 Two out of three examples have little or no trace of markings, 

 but the third is distinctly rayed with broMTi, the rays being- 

 different in the two valves. 



7. Sph^rium VICTORIA, sp. n. (Plate X. fig. 16.) 



Shell roundly subovate, nearly equilateral, greyish yellow, with 

 numerous radiating dark hair-like lines ; valves thin, finely con- 

 centrically striated with the lines of growth, which are crossed by 

 minute microscopic i-adiating strias which are quite invisible to the 

 naked eye ; interior dirty bluish ; lateral teeth dehcate. 



Length 9| millim., diam. 5i, alt. 8|. 



Hah. Dredged in about a fathom in the harbour. 



Larger than S. nyanzce Smith, not quite the same shape, 

 different in colour, rayed, and with more delicate hinge-teeth. 



8. ^THERiA ELLIPTICA Lamarck. 



Hah. Entebbe, north-west end of the lake. 



EXPLANATION OF PLATE X. 



Pigs. 1, 2, 3. Bytltoceras iridescens : p. 182. 

 4. ,, minor : p. 182. 



5, 6, 9. Faramelania dainoni : p. 182. 



7, 8. „ crassigranulata : p. 182. 



10. Lavigeria grandis : p. 182. 



11. 3, „ operculum. 



12. Anceya rvfocincta : p. 183. 



13. Giraudia horei, operculum : p. 183. 



14. „ prcBclara, operculum : p. 183. 



15. Corhicula cwnningtoni\: p. 186. 



16. Sjphcerium victories : p. 186. 



17, 18. A.ncylus tanganyicensis : p. 184. 

 19. IJdgaria nassa, operculum : p. 182. 



