98 AURfS. 



wide concave flange, OTOSTOMUS, p. 107. 



bb. Aperture oblong or sinuous, shorter, lips not concave 



or basin-shaped, EUDOLICHOTIS, p. 108. 



aa. Surface finely granulated spirally ; lip narrow, not sinuous 



or calloused, GONYOSTOMUS, p. 121. 



Subgenus AURIS Spix (s. str.). 

 (=Auris plus Pachyotus, Bulimus of authors). 



Shell umbilicate or rimate, ovate, rather stout, the whorls of the 

 spire distinctly plicate or folded below the sutures, last whorl with or 

 without oblique folds. Aperture ovate, the lip broadly reflexed, 

 often bearing a callous flange. Columella with an oblique fold. 

 Whorls 4| to 5i. Type A. melastoma Swains. 



Distribution, Province of Bahia, Brazil. 



The typical group of Auris consists of rather large ovate species 

 with a series of folds below the sutures, a structure not existing in 

 the other subgenera. Aside from this, there is much in common 

 with Eudolichotis and Otostomus, especially the flange within the outer 

 lip, the tendency to form a basal notch or sinus, and the general 

 coloration. 



Nearly every species of this subgenus occurs under two forms, 

 usually identical in shape, but remarkably distinct in coloring of 

 the mouth parts, and so far as my material shows, there are no in- 

 termediate examples. It is not improbable that this is purely a case 

 of dimorphism, and the forms have no truly varietal status; but as 

 the question has not before been adequately discussed, and observa- 

 tions bearing upon it by naturalists who have seen the species in 

 their native forests are lacking, I have considered the interests of 

 science best served by formal recognition of the several divergent 

 forms, leaving open the question of their status, as one which I have 

 no means of deciding. Compare, in this connection, Dohrn's re- 

 marks in Jahrbiicher d. D. Malak. Gesellsch., x, pp. 348, 349 (1883). 



A study of well-preserved specimens of " Bulimus " aurisvulpina 

 of St. Helena, convinces me that Fischer was entirely right in 

 removing that species from the Pachyotus group. Its conchological 

 features forbid any association of the St. Helena species with South 

 American Bulimi. 



