NO. 2094. MOLLUSKf^ OF THE GENUS RIRS0INA—BART8CH. 57 



well developed, narrow, sinuous, protractive, axial ribs. Intercostal 

 spaces about four times as wide as the ribs, marked by slender, 

 very strong, axial threads. Sutures well impressed. Periphery of 

 the last whorl well rounded. Base rendered concaved in the middle 

 by a slender fasciole at its anterior termination, marked by the 

 feeble continuations of the axial ribs and threads. Aperture large, 

 very oblique, sub-oval, shghtly notched at the posterior angle; outer 

 Hp reinforced by a thick varix immediately behind the edge; inner 

 Hp slender, strongly curved, appressed to the base, parietal wall 

 covered with a thick callus. 



The type. Cat. No. 130562, U.S.N.M., comes from San Pedro, 

 California. It has 5 postnuclear whorls and measures: Length, 2.7 

 mm.; diameter, 1 mm. Cat. No. 271647, U.S.N.M., 1 specimen from 

 Pacific Beach. Cat. No. 225186, U.S.N.M., 2 specimens dredged in 

 3 fathoms off Coronado Island. I have also seen it, from 12 

 fathoms, off Monterey, California. Cat. No. 271648, U.S.N.M., 

 1 specimen from Whites Point, California. Two from the same 

 locality are in Mi's. Oldroyd's collection. One in Dr. Fred Baker's 

 collection came from 3 to 7 fathoms, off Coronados Islandj California. 



RISSOINA WOODWARDII Carpenter. 

 Plate 31, figs. 2, 5. 



Rissaitm woodwardii Carpenter, Cat. Mazatlan Shells, 1856, p. 357. 



Shell small, elongate-ovate, semitranslucent. Nuclear whorls a 

 little more than 3, smooth, forming a well elevated hehcoid apex. 

 Postnuclear whorls well rounded, marked by slender, lameUiform, 

 protractive, axial ribs of which 12 occur upon the first and second 

 and 14 upon the remaining whorls. These ribs are about one-fourth 

 as wide as the spaces that separate them. The intercostal spaces 

 are marked by hues of growth which appear as fine lirations on the 

 early whorls, becoming obsolete on the later. Sutures strongly 

 impressed. Aperture decidedly oblique; posterior angle acute, outer 

 lip thickened at the edge; inner lip very thick, reflected over and 

 appressed to the base, joining this with the outer hp to form a con- 

 tmuous peristome. 



Seventy specimens of this species were collected on Ohama and 

 8'pondylus; 11 of these are on Tablet 1706 in the Liverpool collection 

 at the British Museum and 2 additional ones are on Tablet 1707 at 

 the same place. Doctor Carpenter mentions in his Catalogue of 

 Mazatlan Shells that an unusually large specimen measures: Length, 

 3 mm.; diameter, 0.8 mm. 



I have not seen this species and figure an unpublished camera 

 lucida drawing by Doctor Carpenter of it. 



