1354 MUTEI.A 



Mutela angiistata jickri.!, Faun., N. O. Af., 1874, p. 268, — 



Simpson, Syn., 1900, p. 904. — Germain, I'Afrique Cent. 



Fr., 1907, p. 564. 



Most of the characters of this species are the same as those 

 of ^1/. exotica. But it is a smaller, solider species, the surface 

 is more strongly, concentrically sculptured, and the hinge is 

 edentulous or has only the very^ faintest vestiges of teeth. 



Further study of material received as M. angustata, since 

 the Synopsis was published, leads me to believe that Sower- 

 by's Iridina angiistata is a synonym of dubia. 



Germain, (1. c), states that in his opinion the angiistata 

 Shy. should be considered as a variety of M. nilotica Caill., 

 "from which it differs mainly in the divergence, more or less 

 accentuated, of the dorsal and ventral margins." 



Var. nirta Germain. 



"Shell much less elongated, measuring only 99 mm. in length 

 for a height of 41 mm. and a diameter of 26 mm. Epidemiis 

 emerald-green; nacre rose-salmon, very iridescent."' (Ger- 

 main). 



Type locality. The Lower Chari. 

 Mutela angiistata var. citrta Germain, Bull. Mus. Hist. Nat., 



1906. p. 174, fig. 6; I'Africpie Cent. Fr., 1907, p. 565, fig. 94. 



Var. ponderosa Germain. 



"Valves very thick and heavy ; heavily encrusted with a cal- 

 carious deposit ; striae large and undulating ; nacre bright rose- 

 salmon, very iridescent. 



Length 1 18-149, height 41-64, diam. 28-42 mm." (Ger- 

 main). 



Type locality. Lake Tchad. 

 Mutela angiistata var. ponderosa Germain, Bull. Mus. Hist. 



Nat., 1905, p. 489 ; Ibid, 1906, p. 56, fig. i ; I'Afrique Cent. 



Fr., 1907, p. 565, fig. 95. 



MuTEi.A NILOTICA (Sowcrby). 



Shell elongated, irregularly trapezoid, thin, gaping in front ; 

 umbonal region slightly elevated, elongated ; posterior ridge 

 full, widely rounded: dorsal outline lightly arched; posterior 



