NO. 2207. WEST AMERICAN MELANELLID M0LLU8KS—BARTSCH. 339 



Two specimens of this species (Cat. No. 127542, U.S.N.M.) come 

 from San Hipolito Point, Lower California. The type has 10 post- 

 nuclear whorls and measures— Length, 3 mm,; diameter, 1.2 mm. 



STROMBIFORMIS Da Costa. 



Strombiformis Da Costa, Brit. Conch., 1878, p. 107. Type selected by T. 

 Iredale (Proc. Mai. Sec. London, vol. 11, 1915, pp. 293-295) Strombi- 

 formis glaber Da Costa. 



Very attenuated, slender Melanellids, with very narrow elongated 

 aperture, having the inner lip appressed to the attenuated basal 

 portion of the preceding whorls; marked with one or more spiral 

 color bands. 



STROMBIFORMIS RIVERSI, new species. 



Plate 15, fig. 3. 



Shell large, subulate, yellowish -white with a few famt indications 

 of spiral bands. Early whorls decollated in all the specimens seen, 

 those remaining slightly and evenly rounded, appressed at the 

 summit, separated by an ill-dehned suture, marked by feeble, some- 

 what retractive Hues of growth and irregularly disposed poorly 

 impressed varicial streaks. Suture slightly constricted. Periphery 

 of the last whorl well rounded. Base long, gently rounded. Aper- 

 ture very elongate-ovate; posterior angle acute; outer lip thm; inner 

 lip ratlier long, moderately thick, well rounded, reflected over and 

 appressed to the attenuated base throughout its entire length; 

 parietal wall glazed with a rather thick callus. 



The type and seven specimens of this species were collected by 

 Dr. J. J. Rivers, in the upper San Pedro series, at Santa Monica 

 Canyon, Cahfornia. The type and another specimen are in the col- 

 lection of the United States National Museum (Cat. No. 251390). 

 The rest are in Doctor Rivers's collection. The type has lost the 

 nuclear whorls. The 10 remaining measure— length, 12 mm.; diam- 

 eter, 2.5 mm. 



This is the largest of the West ^'Vmerican members of the genus 

 Stromhiiormis known. 



STROMBIFORMIS ALASKENSIS, new species. 



Plate 45, fig. 1. 



Shell small, straight, yellowish-whito, marked by oxcecdingl}^ line 

 lines of growth only. Whorls rather high, almost flattened, appressed 

 at the summit, separated b}^ a scarcely impressed suture. Periphery 

 of the last whorl well rounded, base moderately long, moderately 

 rounded. Aperture oval; posterior angle acute; outer lip decidedly 

 protracted between the posterior angle and the base; inner lip mod- 

 erately stout, curved, reflected over and appressed to the base; 

 parietal wall glazed with a moderately thick caUus. 



