RETUSA. 225 



whorls 4, rounded, the first mamillate, aperture narrow, dilated in 

 front; coluraella long, semitortuous, umbilicus none (Ad.). 



Borneo (A. Ad.) ; Mauritius (Mobius.) 



Utriculus borneensis A. AD.. Thes. Conch, ii, p. 572, pi. 120, f. 

 23. SOWB., Conch. Icon. f. 6. v. MARTENS, in Mobius' Reise n. 

 Mauritius, p. 303. 



A much smaller shell than B. cecillii. It is narrower, more cyl- 

 indrical ; the aperture is more produced anteriorly ; the colu- 

 mella is longer and straighter, and the spire is more depressed. The 

 mud flats at the mouths of many of the rivers of Borneo are parti- 

 ally covered at low water with this animal; the shell is always cov- 

 ered, when the animal is alive, with a rust-colored epidermis (Ad.). 



R. COMPLANATA Watson. PI. 21, fig. 2. 



Shell minute, cylindrical, truncated and flat on top, very much 

 and obliquely truncated in front, with whorls angulated above and 

 furrowed longitudinally and spirally, a papillary apex, a longish 

 pillar, and a club-shaped mouth. Sculpture: Longitudinals the 

 furrows on the lines of growth are strong and curved. Spirals 

 the whole surface is scored with sharp irregular furrows parted by 

 flat intervals of about three times their width. Color white.. 

 Mouth the full length of the shell, narrow above, oblong and roomy 

 in front, club-shaped. Whorls 3 ; on the top of the shell they are 

 rounded. Suture slightly impressed. Outer lip rises roundly, the 

 least thing above the top ; its course is straight, with a very slight 

 concavity; its edge is prominent. Top perfectly flat, with a 

 roundly angulated edge ; the individual whorls are rounded, and 

 are parted by a somewhat impressed suture ; the central tip, which 

 is glossy, is papillary, but depressed. Inner lip is, on the body, 

 slightly concave in its course ; the pillar is oblique, nearly straight,, 

 and is patulous. Alt. 0'05 in., diam. 0'028. Breadth of mouth at 

 same place, 0'013 inch (Wats.). 



West of Cape York, off southwest point of Papua, 28 fms. 



Utriculus complanatus WATS., J. L. S. L. xvii, p. 335 ; Chall. 

 Rep. Gastr. p. 650, pi. 48, f. 9. 



This is a very small species, the solitary specimen of which is not 

 in good condition. It is a good deal like Utriculus truncatulus 

 (Brug.) ; but the sculpture is a very marked feature of difference,, 

 and the form is more stumpy ( Wats.). 



