dall: mollusca and braciiiopoda. 289 



and protractive axial ribs which extend from the suture to the canal except over 

 tlie last half of the last whorl ; the constriction which indicates the anal fascicle 

 gives the posterior edge of tlie whorl a niarginate appearance, but does not inter- 

 rupt the ribs, which are very prominent in front of the fascicle at the shoulder ; 

 the whole surface is evenly sculptured by strongly incised, almost channelled lines, 

 with wider, flat, strap-like interspaces ; near the canal these become narrower and 

 cord-like and the channels wider, diminisliing again toward the end of the canal ; 

 the spiral sculpture does not nodulate the ribs, but is minutely crenulated on the 

 eminences by fine, even, incremental lines; aperture short, wide, witli a deep 

 rounded anal sulcus next the suture, a thin and much produced outer lip, a short, 

 slightly recurved, flaring canal, an arcuate callous pillar, white and smooth, with 

 a conspicuous nodule on the body between the sulcus and the suture ; operculum 

 wanting. Lon., 14; of last whorl, 8 ; of aperture, 5.5; max. diam. 6 mm. 



U. S. S. "Albatross," station 3391, in the Gulf of Panama, 153 fathoms, mud, 

 bottom temperature 55°.8 F. U. S. N. Mus. 123,104. 



The species was also dredged at station 2804, in Panama Bay, in 47 fathoms, 

 mud, bottom temperature 64° F. U. S. N. Mus. 122,771. 



Tiie first half of the last whorl in the adult ends in a node or varix, indicating 

 a previous resting stage with developed outer lip; beyond this the whorl is desti- 

 tute of ribs. 



Clathurella plicatella Dall, n. sp. 



Shell very small, acute, eight-whorled, flesli color or pinkish white, polished; 

 nucleus turbinate, blunt, polished, smooth, of about two whorls ; subsequent 

 whorls axially sculptured with (on the last whorl behind the node) ten sharp, 

 more or less sigmoid, slightly protractive ribs extending from the suture to the 

 canal, or on the spire from suture to suture, with wider interspaces ; suture 

 appressed ; in front of it is a very slight constriction corresponding to an anal 

 fasciole, though no actual fasciole is visible ; aperture moderate, anal sulcus large 

 for the size of the shell, rounded and deep; lip in front of it rounded and pro- 

 duced ; on the body a small mass of callus limits the posterior edge of the sulcus ; 

 the body is smooth and callous, the enamel extending upon the pillar, whicli is 

 short and attenuated ; canal short, recurved, on the back finely, sharply, spirally 

 striated, but these striae do not extend over the rotundity of the whorl. Length 

 of shell, 7.0; of last whorl, 3.5; of aperture, 2.5; max. diam. 2.5 mm. 



U. S. S. " Albatross," station 2799, in Panama Bay, in 29J fathoms, mud. 



This pretty little species is a typical Clathurella. 



GLYPIIOSTO:?IA Gabr. 

 Glyphostoma immaculata Dai.l, n. ep. 



rinte 1, flKTiire 9. 



Shell small, white, with a faint brownish or pinkish flush on the last whorl 

 brilliantly polished and witli no perceptible periostracum or operculum ; nucleus 



VOL. XLIII. — NO. 6 19 



