638 MEMOIRS OF THE CARNEGIE MUSEUM. 



of the trapesiali s-group of Anodontites, with which it also has in common the gaping 

 margins. A pecuHar character, generally missing in South American Mutelince, 

 is the presence of an oblique row of dorsal muscle-scars in the beak-cavity. 



There can be hardly any question that this genus represents a more highly 

 specialized type of the genus Anodontites, and that its root is in the trapesialis- 

 group. Its distribution extends over South America, east of the Andes, and from 

 the basin of the Amazon southward to northern Argentina. 



The genus Leila is in great confusion, although there seem to exist only a 

 few species. Its revision has been attempted by Von Ihering (1890, p. 39) and 

 by Simpson, (1900, p. 914), but these two authors have arrived at very different 

 conclusions. Both agree in recognizing two groups: the one containing species 

 with a practically straiglit hinge-line (L. blainvilleana and L. spixi), the other 

 species with a curved or sinuate hinge-line. While Simpson unites all of the forms 

 belonging to the latter group, into one species (L. esula), Von Ihering distinguishes 

 three as valid. 



My material is entirely insufficient to permit me to decide this point. The 

 specimens before me unquestionaly come under L. castelnaudi Hupe, and so I shall 

 record them under this name, without attempting to pass upon the question 

 whether then are different from esula D'Orbigny and from pulvinata Hupe. They 

 also agree fairly well with Von Ihering's description of castelnaudi. 



09. Leila castelnaudi Hupe (1857). 

 Leila castelnaudi Hupe, 1857, p. 91, PI. 19, fig. 1. 

 Anodon castelnaudi Sowerby, XVII, 1868, PL 20, fig. 79. 

 Columba castelnaudi Von Ihering, 1890, pp. 139, 142. 



According to Simpson (1914, p. 1401) this is identical with L. esula (D'Orbigny). 



Type-locality. — "Bourbon ou Olympo, Paraguay." This probably is Fuerte 

 Olympo, on Rio Paraguay, northern Paraguay. 



New Localities. — Rio Paraguay, Corumba, Matto Grosso, Brazil (H. H. 

 Smith coll.). One left valve. Swamp of Lambare, Asuncion, Paraguay (J. D. 

 Haseman coll., March 31, 1909). One left valve. 



Measurements. 



Von Ihering has measured according to a peculiar method, but I see no par- 



