ortmann: south American naiades. 589 



rf:. SIr'II suhovate or sublraiHV.oiilal. Prismatic bonlci- iianow and (jf ('(lual width. 



Oroup of .1. IraiHsialu. 

 a;. Shell greatly elongated, sharply pointed behind, with a sharp posterior ridge. Posterior retractor- 

 scar completely separated from adductor-scar. Epidermis not shining, covered with fine wrinkles. 



Subgenus Lamproscapha. 



Subgenus Anodontites s. s. 

 Anodontitcs s. s. + Styganodon Von Martens, Simpson, 1914, pp. 1403, 1448. 



Shell of various shapes, but not greatly elongated or pointed behind, without 

 sharp posterior ridge. Posterior retractor-scar connected with adductor-scar. 



1. Group of Anodontites crispata. 

 Group of .4. crispatus Simpson, 1914, p. 1414 (pars) + Section Stijganodon, group 



of A. tenebricosus, Simpson, ibid., p. 1448. 



Shell not, or very little, obliciue, subtrapezoidal, rather elongated, with the 

 lower margin straight or more or less concave (sinuated). Epidermis dull, dark, 

 not rayed, not smooth, but strongly and densely sculptured all over by concentric 

 or radial, or irregular wrinkles. Prismatic border narrow or wider, of nearly equal 



width. 



The most essential feature of this group is in the texture of the epidermis, 

 and its somber color. The nacre also is peculiar, being dull and lurid. 



These forms greatly resemble certain African species of Spatha, subgenus 

 Aspatharia, and I am strongly inclined to think that of all South American types 

 of Mutelince these show the closest affinities to that African group. In A. crispata 

 occasionally a single dorsal muscle-scar is present, which also agrees with the con- 

 dition regularly seen in Spatha. 



Three species belonging here are known to me in nature. They may be dis- 

 tinguished as follows : 



ai. Wrinkles of epidermis arranged concentrically and radially, the radial tendency prevailing. Pris- 

 matic border moderate --i- crispata. 



0-2. Wrinkles of epidermis with concentric tendency prevailing, radial arrangement obscure. 



bi. Shell comparatively shorter and higher, beaks more median in position A. tenebrtcosa. 



62. Shell comparatively longer and lower, beaks more anterior in position .4. clessmi. 



48. Anondontites crispata-^ Bruguiere (1792). 



Shells: Plate XL, figs. 7, 8; Plate XLI, figs. 2, 3. 



Anodontites crispata Bruguiere, Journ. Hist. Nat. Paris, I, 1792, p. 131; Simpson, 



1914, p. 1415. 

 Anodon rcticulatus Sowerby, XVII, 1867, PI. 10, fig. 27. 



-^ Bruguiere uses Anudontites us fcminini generis, and this should not be changed. 



