1356 MUTELA 



MUTF.LA ALATA (Lea). 



Shell trapezoid, suhcompressed, subsolid, inequilateral ; 

 beaks not elevated above the dorsal line ; posterior ridge low, 

 subangulate, the dorsal slope above it being radially exca- 

 vated so as to produce a wide, shallow furrow ; dorsal line 

 straight, the hinder part raised into a decided wing, which is 

 almost squarely subtruncate behind ; anterior end narrow, 

 rounded, base nearly straight, slightly incurved medially, the 

 outline curved up behind ; surface with fine irregular, con- 

 centric sculpture ; epidermis yellowish-green, bronzy and iri- 

 descent ; hinge edentulous ; muscle scars impressed ; dorsal and 

 anterior scars very irregular ; posterior scars double ; nacre 

 rose or coppery-tinted, iridescent. 



Length 80, height 45.5, diam. 19 mm. 



Lake Nyassa. 

 Spatha alaia Lea, Pr. Ac. N. Sci. Phila., 1864, p. 109; Jl. Ac. 



N. Sci. Phila., 1866, p. 35, pi. xii, fig. 31 ; Obs., XL 1867, P- 



39, pi. XII, fig. 31. 

 Platiris (Spatha) alata Lea, Syn., 1870, p. 89. 

 Mutela alata Clesstn, Conch. Cab. Ano., 1876, p. 196, pi. lxii, 



figs. 7, 8. — Stmpsox, Syn., 1900, p. 904. 

 Burtonia alata Ancey, Bull. Mai. Fr., VL 1889, P- 3^- 



This is a beautiful species with a rich, iridescent epidennis, 

 which shows shadings of yellowish-green and bright green. 

 It is, no doubt, closely related to J\I. simpsoni, but is more 

 ':ompressed. is more strongly winged, and does not show the 

 strong, radial furrows on the front of the disk that Ance_v's 

 species does. Lea's shell shows faint indications of radial 

 sculpture in front ; it also gapes at the anterior base and slight- 

 ly behind. The posterior end of his shell is somewhat diseased. 



Mutela simpsoni Ancey. 



Shell only slightly elongated, subsolid, gaping in front and 

 behind, trapezoid, inequilateral, subinflated ; beaks low ; dorsal 

 outline straight in front, lightly winged behind; posterior end 

 obli(iuely truncated : anterior end angled above, rounded be- 



