BALL: MOLLUSCA AND BRACHIOPODA. 287 



is more or less constricted ; at the shoulder begin about fifteen short, very ob- 

 liquely protractive, ■wave-like ribs, with narrower interspaces, ■which are con- 

 spicuous only near tiie peripliery ; surface otherwise smooth except for faint 

 incremental lines ; aperture lunate ; anal sulcus wide, shallow ; outer lip sharp, 

 thin, arcuately produced in front of the sulcus; body polished; pillar short, 

 gyrate, not pervious, obliquely truncate in front ; caual very short, wide, and 

 slightly recurved. Lon. of shell, 10.5 ; of last whorl, 6.5 ; of aperture, 5.0 ; 

 max. diam. 4.6. mm. Operculum none. 



U. S. S. "Albatross," station 3392, Gulf of Panama, in 1270 fathoms, hard 

 bottom, temperature 36°. 4 E. U. S. N. Mus. 123,131 ; and station 3393, in 

 1020 fathoms, mud, temperature 36°.8 F. U. S. N. Mus. 123,122. 



This and the preceding species are not of the typical group of Maugilia, having 

 more the profile of a Gemmula with a short canal, or a small, slender, high-spired 

 Gymnobela, but they are left here for the present, pending a revision of the entire 

 group. 



Mangilia sedillina Dall, n. ep. 



Plate 13, figure 8. 



Shell small, translucent white, very thin, fusiform, the nucleus eroded, with 

 four subsequent whorls ; suture distinct, whorl in front of it with a narrow, thick- 

 ened margin ; whorls slightly angulated at the shoulder, the angle obsolete on 

 the last whorl; axial sculpture, in addition to lines of growth of (on the penulti- 

 mate whorl abcut twenty-six) fine, sharp, narrow lamellose riblets following the 

 lines of growth, beading the presutural band, angulated at the shoulder and obso- 

 lete on the base, with wider, excavated interspaces ; these are crossed by very 

 numerous, fine, close-set, spiral threads, slightly coarser on the canal and 

 minutely feebly reticulated by the incremental lines; body and pillar polished, 

 the sculpture erased ; outer lip thin, simple, with a wide sulcus occupying the 

 space between the suture and the shoulder, in front of which it is arcuately pro- 

 tractive; pillar straight, simple, obliquely truncate in front; caual short, wide, 

 not recurved. Operculum absent. 



Variety with stronger sculpture, shorter and stouter shell, and distinctly re- 

 curved canal. 



Lon. of (decollate) shell, 8.0; last whorl, 6.7; aperture, 5.0; mas. diam. 

 4.0 mm. Same dimensions in the variety, 5.7, 4.5, 4.0, and 3.5 mm. 



U. S. S. "Albatross," station 3392, Gulf of Panama, in 1270 fathoms, hard 

 bottom, temperature 36°.4 F. U. S. N. Mus. 123,116 aud 123,116 a. 



Mangilia encella Dall, n. ep. 



Plate 14, flKure 11. 



Shell small, white, with a translucent thin pcriostracum and about fire whorls 

 (the nucleus eroded); spire sligiitly longer than the aperture; early whorls 

 rounded with about fifteen slender, low, arcuate, protractive, axial riblets which arc 



