182 Proceedings of the Biological Society of Washington. 



Were it not for the deep purple interior, I would be inclined to consider 

 these albinistic specimens of Oliva tricolor, but the color of the interior 

 leads me to believe that we are dealing with a distinct race. 



Mitra nigritella, new species. 



Shell very elongate ovate, very dark brown excepting a narrow white 

 zone which encircles the whorls immediately above the periphery. Nuclear 

 whorls well rounded, feebly, roundly shouldered at the summit. Post- 

 nuclear whorls marked by rather strong moderately broad, almost vertical 

 axial ribs, which are eroded on the earlier turns but of which eighteen occur 

 upon the fourth, twenty upon the remaining turns, of the type. In addi- 

 tion to the axial ribs which extend feebly to the very apex of the base on 

 the last turn, the entire surface is marked by fine lines of growth. The 

 spiral sculpture consists of slightly sinuous threads which are equal and 

 sub-equally spaced. Of these threads, eight occur between the summit 

 and the suture on the last turn. Suture strongly marked. Base marked 

 in addition to the continuations of the axial ribs on the anterior half by 

 nine spiral threads equalling those of the spire in strength and on the 

 anterior half by six cords, which are much stronger and more distantly 

 spaced, and which render their junctions with the ribs slightly nodulose. A 

 strong tumidity encircles the base at the anterior columellar fold. Aper- 

 ture narrow; posterior angle acute, decidedly channeled anteriorly; outer 

 lip somewhat sinuous; inner lip reflected over and appressed to the base, 

 provided with three oblique folds which decrease in size successively from 

 the posterior anteriorly; parietal wall covered by a moderately thick callus, 

 which is of equal strength throughout its extent. 



The type and another specimen of this species, Cat. No. 219,054, U. S. 

 N. M., Coll. No. 110, were collected by Mr. Weber at Bugsuk Island. 

 The type has 7 whorls remaining and measures: length, 17.2 mm., dia- 

 meter, 7.1 mm. 



Mitra palawanensis, new species. 



Shell elongate ovate, Sanford brown, a little paler at the tip. Nuclear 

 whorls decollated in all of our specimens. Postnuclear whorls well rounded, 

 marked by strong spiral keels which are slightly flattened on their summit. 

 Of these keels, three occur between the summit of the whorls and the 

 suture on the early whorls; the summit gradually dropping on the whorls 

 permits a fourth one to be present on the spire of the last turn. The first 

 of these keels, which are equally spaced, is almost as far from the summit 

 as it is from its anterior neighbor. The spaces between the spiral keels, 

 which are about twice as wide as these, are shallow grooves. In addition 

 to the spiral sculpture the whorls are marked by numerous closely spaced, 

 slightly, retractively slanting, incised lines which pass over the spiral 

 keels, but are best marked in the depressions. Periphery of the last whorl 

 well rounded. Base rather elongated, slightly concave in the middle, 

 marked by spiral keels of which six equal those of the spire in strength 

 and spacing. These occupy the posterior two-thirds of the base. Five 



