Shells from W, st Afrtou 80 



covoit'il witli a coarsely laminiferoiis roddi.sli-ljrowti peri- 

 ostracum ; interior of sliell whitish, gradii.illy changing to 

 dark blacki.sh purple. 



Lf»n^. 11, Int. tI25 nun. 



Hah. Banana Creek, C'oncro Doha. 



Separable from D. Utcnstris, .Murl.*, hy its much hroaier 

 and tnore trigonal form, its more laininiterous periostracum, 

 and darker interior, which in l>, lucustris is (juite white. 



Dreissenfia gibherosa^ sp. n. (Fig. 4.) 



Shell incquivalve, mytiliform, rather sharply curved, 

 broad in proportion to its length, covered with a dark brown 

 laminiferous periostracum ; interior of shell bluish white, 

 stained in places with greyish brown and pencilled with 

 lontjitutlinal grevisli-brown lines. 



Ijong. 20, hit. 115 mm. 



Ilah. Assinie. 



Differing from D. ornata, Mori., its nearest ally, in being 

 much larger and smoother; the pencilled lines in the interior 

 are also n)uch coarser. 



C^nio {XoJularia) subnigra, sp. n. (Fig. 5.) 



Shell oblong-ovate,covered witii a dark brown periostracum, 

 -mooth centrally, but becoming laminit'erous towards the 

 margins, especially posteriorly ; uraboes moderately small, 

 >ituated subcentrally ; dorsal margin slightly arched ; ventral 

 margin gently curved ; anterior side flattened, bluntly 

 rounded ; posterior side very obtusely angled ; left valve 

 bearing a cardinal jagged lamellitbrm tootli ; anterior teeth 

 wedge-shaped, with jagged edges ; posterior teeth fine, elon- 

 gate, smooth ; interior of shell pale flesh-colour, changing 

 towards the anterior and posterior margins to iridescent livid 

 blue. 



Long. 31".5, lat. 49 mm. 



JIaO. Lower Belgian Congo. 



Mufela Ihotelleriana, sp. n. (Fig. G.) 



Shell rhomboidal, slightly gaping at both sides, covered 

 with an olivc-grecn periostracum, marked with coarse irre- 

 gular concentric lines of growth and indistinct radiate ridges, 

 a minute oblique striate sculpture being apparent in places 

 under a lens; umboes small, not prominent, situated very 



• Morltt, Jniirn. de Conch. 1«8.'), p. •V2. 

 Ann. (0 }(a<j. X. Hist. Ser. 8. I'ol. iv. 7 



