1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 373 
Compared with P. curta it differs by the less swollen shape, low 
beaks, straight margins on both sides of the beaks, light colored interior, 
etc. | : | 
In one specimen the anterior end is more broadly rounded than in 
the others. The degree of development of convexity of the ventral 
margin, corresponding to a swelling in the middle of the valves, varies 
individually (or possibly sexually). 
We are not wholly satisfied that this species is really distinct from 
I. levigata (Gmelin); but we have not been able to compare young 
rostrata of the size of levigata. 
a 
Fig 83  a-c, Iphigenia congo Pilsbry and Bequaert. Type. Malela. 
Iphigenia congo, new species 
Text Figure 83a-c 
?Fischeria delessertii “Bernardi.” 'C. R. Barrenr, 1913, Ann. Soc. Zool. 
Malacol. B:lgique, XLVII, (1912), p- 114 (Lower Congo and San Antonio, in com- 
pany with J. lenzi; P. Hesse Coll.). 
Malela (Lang, Chapin, and J. Bequaert Coll.). 
The shell is elliptical, thin, the dorsal and ventral margins about equally curved; 
moderately plump. The anterior end is rounded, the posterior end is narrower, 
rounded Beaks median, low, projecting but little above the hinge. Lunule narrow, a 
little shorter than the ligament. Periostracum dull, olive-brown (sometimes obscurely 
