60 PROCEEDINGl^ OP THE ^'AT10yAL MUSEUM. vol.49. 



and measures: Length, 2.8 mm.; diameter, 1 mm. Sixty-one speci- 

 mens were examined from the same locality, in Mrs. Oldroyd's collec- 

 tion. Cat. No. 129334, U.S.N.M., contains 8 specimens from San 

 Pedro. Cat. No. 225187, U.S.N.M., 3 specimens, dredged in 3 

 fathoms off South Coronado Island. 



RISSOINA CORONADENSIS. new species. 

 Plate 33, fig. 8. 



Shell small, elongate-conic, milk white. Nuclear whorls a little 

 more than 2, well rounded, smooth. Postnuclear whorls moderately 

 rounded, appressed at the summit, the appressed portion slightly 

 excurved, marked by slender, slightly protractive, somewhat sinuous, 

 axial threads of which 40 occur upon the hrst, 42 upon the second, 

 48 upon the third, 56 upon the fourth, and 52 upon the penultimate 

 turn. These threads are separated by intercostal spaces about as wide 

 as the tlii-eads. Suture well impressed. Periphery of the last whorl 

 well rounded. Base rather short, slightly concaved, marked by the 

 continuations of the axial threads which extend undiminished to the 

 umbilical area. Aperture oval, posterior angle acute; outer Up thin 

 at the edge, thickened immediately behind the edge by a varix, thin 

 deep within where the external sculpture shines through the sub- 

 stance of the shell; inner hp short, strongly curved, reflected over 

 and adnate to the base; parietal wall covered with a thick callus 

 which renders the peritreme complete. 



The type, Cat. No. 271649, U.S.N.M., was dredged by the U. S. 

 Bureau of Fisheries steamer Albatross at station 2932 m 20 fathoms, 

 on gray sand and broken shell bottom, bottom temperature 58°, off' 

 Los Coronados Islands. The type has 6 postnuclear whorls and 

 measures: Length, 3.5 mm.; diameter, 1.3 mm. Cat. No. 271650, 

 U.S.N.M., 1 specimen, dredged by the Albatross at station 4309 in 

 67 to 78 fathoms on sand, shell and rocky bottom, oft' Point Loma, 

 California. Cat. No. 162663, U.S.N.M., 1 specunen from San Martin 

 Island, Lower California. 



RISSOINA JANUS C. B. Adams. 



riatc 32, fig. 8. 



Rissoajanus C. B. Adams, Ann. Lye. Nat. Hist. N. Y., vol. 5, 1852, p. 403. 



The type of R. janus in the Amherst collection, collected by C. B. 

 Adams, at Panama, is a very badly worn medium sized Rissoina, in 

 which the ribs have been worn down to such an extent that one can 

 scarcely count them. There are probably 20 on each of the last 2 

 whorls. It is absolutely impossible to decide whether spiral sculpture 

 may have been present or absent. The only thmg that will help in 

 the identification of the present form with good material is the out- 

 line. The part of the original description referrmg to this character 

 evidently belongs to var. a, which is now named R. adamsi. 



