1364 MUTELA , 



ascending; ventral margin long- and regularly subconvex ; an- 

 tero-dorsal angle well marked; anterior region very short, 

 rounded, cut away at the base ; posterior region remarkably 

 developed, more than 5 1-2 times as long as the anterior, ter- 

 minating in a long, well-rounded beak: beaks small, only 

 slightly prominent, much eroded ; dorsal ridge at first promi- 

 nent, but nmch reduced towards the extremity ; ligament very 

 long, strong, somewhat prominent, brilliant brown, length 53 

 mm ; hinge filiform ; anterior muscular impressions quite deep, 

 posterior feeble, but quite visible, pallial well marked. Epi- 

 dermis light chestnut-color, yellowish in the centre of the disk 

 and towards the margins, eroded towards beaks, revealing a 

 very iridescent, salmon-tinted nacre ; lines of growth quite 

 fine, not very regular, light in the middle, becoming- stronger 

 and somewhat lamellose towards the posterior region ; nacre 

 brilliantly iridescent, salmon-color under the beaks, greenish- 

 blue towards the margins. 



Length 117, height 30 mm. at 55.5 mm. from the beaks, in 

 front of the beaks 31, length of the anterior region 17.5, of 

 the posterior region loi, diam. 18 mm." (Germain). 



Type locality. The Upper Oubangui. 

 Mmtelina joubini Gkraiain, Bull. Mus. Hist. Nat., 1904, p. 



470 ; I'Afrique Cent, Fr., 1907. p. 572, pi. lith., fig. 2. 



"This magnificent species can be compared only with Miitel- 

 ina plicoto Sowerby. It is to be distinguished by its much long- 

 er posterior region, which is not tnmcate at the end, but very 

 regularly ovally rounded ; by its greatest height being nearer 

 to the beaks, which are notably smaller and less prominent, 

 etc.'' 



SPECIES INCERT.^v SEDIS. 

 MuTELA i,'hotf,i.i,e«iana Preston. 



"Shell rhomboidal, slightly gaping at both sides, covered 

 with an olive-green periostracum, marked with coarse, irreg- 

 ular, 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 an- 



