1346 STATU A 



and irregularly, concentrically sculptured; epidennis suboliva- 

 ceous-chestnut, slightly shining: nacre suboliyaceous to whit- 

 ish. 



Length 55, height 33, diani. 15 mm. 



Lake Tanganyika. 

 Moncetia moineti lUn rcuicnat, Un. and Ir., 1886, p. 61 ; Icon. 



Mai. 1888, pi. XXX. fig. 7. 

 Moncetia rochehruucana Bourguignat, Nouy. Mai., 1886, p. 



62; Icon. Mai.. 1888. pi. xxx, fig. 8. 

 Spatha monieti Simpson, Syn., 1900, p. 901. 



The sculpture is apparently less ragged than in 5^. ancexi 

 and the nacre is rose-tinted. The Moncetia rocliebnmeana, as 

 figured by Bourguignat in his Iconographie, is a specimen with 

 the posterior end badly diseased and does not seem to me to 

 dififer otherwise from moineti. The anterior end gapes slightly. 



Spatiia lavigertna (lio'Urguignat). 



Shell compressed, somewhat elongated, lightly arcuate, in- 

 equilateral : beaks low ; dorsal outline arched ; basal outline a 

 little incuryed ; anterior end rounded, angled above ; posterior 

 ridge haying a tendency to be double, ending in a feeble bian- 

 gulation at the base of the shell, with a faint, wide, radial 

 ridge above it ; dorsal slope lightly, obliquely truncate ; sur- 

 face densely, concentrically sculptured ; epidermis fuscous 

 chestnut to yellowish ; sometimes having greenish rays behind ; 

 nacre white to violet-tinted, bright. 



Length 61, height 2^2, diam. 15 mm. 



Lake Tanganyika. 

 Moncetia lai'ii^crina Bourguignat, Nouv. Mai., 1886, p. 60; 



Icon. Mai., 1888, pi. xxx, fig. 6. 

 Spatha laz'is^erina Simpson, Syn., 1900, p. 901. 

 Moncetia bridonxi Bourguignat, Un. and Ir., 1886, p. 65 ; 



Icon. Mai,, 1888. pi. xxx, fig. 5. 



'i'he posterior end of this is wider than in the other forms 

 and is somewhat biangulate. The M. bridonxi seems to me 

 to be a voung shell, which is slightly rayed behind. 



