SP\THA 1345 



vSpatha ANCiSYi (Bourguignat). 



Shell elongated, subrhomboid, compressed, inequilateral ; 

 beaks low, sharply striate ; dorsal and basal lines nearly paral- 

 lel, the former arched, the latter slightly incurved so that the 

 shell is slightly arcuate ; anterior end rounded ; posterior end 

 obliquely truncate or subtruncate above ; surface rudely and 

 very irregularly concentrically sculptured, the margins of the 

 ridges being apparently ragged ; epidermis earthy-yellow, 

 paler at the beaks ; nacre bluish-white, slightly iridescent ; right 

 valve with a sort of obsolete tooth near the beak, left valve 

 with a sort of rudimentary lateral ; dorsal scars double or 

 treble. 



Length 52, height 24, diam. 13 mm. 



Lake Tanganyika. 

 Moncetia anceyi Bourguignat, Esp. Ouk., 1885, p. 34 ; Icon. 



Mai., 1888, pi. XXX, f^g. I. 

 Moncetia jouberti Bourguignat, Un. and Ir., 1886, p. 63 ; 



Icon. Mai., 1888, pi. xxx, fig. 4. 

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

 Spatha (Moncetia) anceyi Germain, Arch. Zool. Exp. et Gen., 



('5), I, 1909, p. 50. 



I have placed this and two other apparently related species, 

 which their author Bourguignat has put in the genus Moncetia, 

 as a subgenus under Spatha. I have never seen any of the 

 forms belonging to this group and it may be that it should 

 have generic rank. M . jouberti seems to me to be merely an 

 old M. anceyi, which is more arcuate and somewhat drawn out 

 at the posterior base. The shells gape in front and are thinner 

 medially. 



Germain. (1. c.^i, unites all the species of Moncetia under 

 this species. 



Spatha moineti ( Bourguignat"). 



Shell compressed, rather solid, arcuate, irregularly rhom- 

 boid, inequilateral ; beaks low ; dorsal outline strongly arched ; 

 base incurved : anterior end a little narrowed, subangulate 

 above ; dorsal slope obliquely subtruncate ; surface strongly 



