278 bulletin: museum of comparative zoology. 



plication at the proximal end of the pillar ; axis impervious, caual short, ■wide, 

 deep, sliglitly recurved with a fairly well-marked fascicle. Lon. of shell, 29.0 ; of 

 last whorl, 1G.5 ; of apertm-e, 12.0 ; max. diam. 9.0 mm. 



U. S. S. " Albatross," station 2931, off Los Coronados Islands, California, in 

 34 fathoms, sand, bottom temperature 56° F. U. S. N. Mus. 110,608. 



This is nearest B. dalli Arnold, but of a different color, more slender, and on 

 the last whorl has the flattened fasciolar area very much wider. The fold ou the 

 pillar is easily visible. 



PLEUROTOinELLA Yekrill. 



Pleurotomella (Qymnobela) agonia Dall. 



Plate 1, figure 6. 



Pleurotomella (Gymnobela) agonia Dall, Proc. U. S. Nat. Mu8., 1889, 12, p. 307, pi. 6, 

 fig. 4. 



Shell large, thin, chalky, with a pale straw-colored periostracum ; form biconic, 

 with a presumably blunt, eroded apex and about seven whorls ; suture distinct, 

 minutely channelled ; the margin in front of the suture is turgid and pinched up 

 into numerous short, narrow, obliquely retractive small folds with wider interspaces 

 and rounded summits ; these become obsolete on the last whorl ; there are about 

 twenty-one on the penultimate whorl, and they do not cross the anal fasciole which 

 is gently excavated ; on the shoulder of the whorl are a series of lunate projections 

 corresponding to the anal sulci (about nineteen on the penult whorl) less distinct 

 and prominent than the sutural folds but larger : the whole surface is spirally 

 sculptured with small low flattish ridges finer and closer on each side of the shoulder 

 but elsewhere subequal and nearly equidistant, with subequal interspaces which 

 become somewhat wider near the canal ; there are also numerous very fine spiral 

 striae and lines of growth forming a microscopic obscure reticulation; base 

 rounded, attenuate in front; outer lip (defective) thin, simple, with a wide shallow 

 anal sulcus at the shoulder ; body and pillar slightly callous, with the appearance 

 (which may be pathological) of an internal spiral ridge on the pillar not visible 

 from the aperture ; pillar straight, very obliquely truncate and twisted in front ; 

 canal moderately wide, not recurved. Lon. of (decollate) shell, 25 ; of last whorl, 

 18.5 ; of aperture, 14 ; max. diam. 12 mm. 



U. S. S. " Albatross," station 2808, near the Galapagos Islands, in 634 fath- 

 oms, coral sand, bottom temperature 40° F. U. S. N. Mus. 96,493. Also at 

 2807, in 812 fathoms, ooze, temperature 38°. 4. 



Pleurotomella (Gymnobela) agonia var. altina Dall, nov. 



IMnto 14, figure 9. 



Sliell large, thin, pinkish brown, biconic, spire slightly longer than the aperture 

 with seven well-rounded whnrls in addition to the (lost) nucleus; suture dis- 



