652 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 52. 



TURBONILLA (PYRGISCUS) ALMEJASENSIS. new species. 



Plate 45, fig. 10. 



Shell slender, elongate conic, milk white. Xuclear whorls decol- 

 lated in the type (see end of description for this character). The 

 early postnuclear whorls are flattened, the later ones well rounded; 

 all have the summit feel)ly shouldered. The whorls are ornamented 

 by very regular well rounded axial ribs which become somewhat en- 

 feebled toward the summit. These ribs have a decided protractive 

 slant on the early whorls, while on the middle turns they are ver- 

 tical, and on the later volutions they have a decidedly retractive 

 slant; here, too, they are a little less strong and less regular and 

 much more closely spaced. Of these ribs 18 occur upon the first four 

 of the remaining turns, 20 upon the fifth, 22 upon the sixth, 24 upon 

 the seventh, 28 upon the eighth, 34: upon the ninth, 36 upon the 

 tenth, and about 52 upon the last turn. Intercostal spaces a little 

 narrower than the ribs, marked by 15 fairly equal and equally spaced 

 spiral series of pits, which are about as wide as the spaces that sepa- 

 rate them. Of these pits the first is about one-twelfth the distance 

 between the first basal line and the peripheral series of pits anterior 

 to the summit. On the last whorl, where the axial ribs become de- 

 cidedly enfeebled, the combination of the axial and raised spiral 

 sculpture gives to the surface a thimble pitted appearance. Suture 

 of the early whorls slightly and of the later strongly constricted. 

 Periphery of the last whorl well rounded. Base attenuated, marked 

 by the very feeble continuations of the axial ribs, and 12 incised 

 spiral lines, which are of irregular strength and spacing. Aperture 

 broadly oval ; posterior angle acute ; outer lip thin ; inner lip slightly 

 curved, decidedly oblique, revolute, and appressed to the attenu- 

 ated base for almost its entire length, provided with a strong very 

 oblique fold at its insertion; parietal wall covered by a very thick 

 callus. 



The type, Cat. No. 266535, U.S.N.M., was dredged in shallow water 

 in Almejas Bay, which is really the southern arm of Magdalena Bay, 

 Lower California. The type had lost the nucleus and probably the 

 first postnuclear turn, the 12 whorls remaining measure — length, 

 8 mm.; diameter, 1.1 mm. Cat. No. 267717 contains two additional 

 specimens dredged in shallow water in Santa Maria Bay, Lower 

 California. From these we are able to add a description of the 

 nucleus. Nuclear whorls 2|, well rounded, forming a moderately 

 elevated spire, the axis of which is at right angles to that of the 

 succeeding turns, in the first of which the tilted spire is one-fifth 

 immersed. 



