MOLLTJSCA OP THE ' CHALLENGER ' EXPEDITION. 337 



Shell. — Small, rather broadly cylindrical, but contracted in the 

 middle, and broadest below the contraction, very bluntly rounded 

 in front, longitiidinally striate and very finely spiralled, with a 

 flat but slightly depressed crown and a small papillary apex. 

 Sculpture. Longitudinals — there are a great many small hair- 

 like ridges and furrows on the lines of growth ; they are no- 

 where strong, but are feeblest on the base. Spirals — the whole 

 surface is very equally striated, with delicate shallow scratched 

 lines parted by flat surfaces 4 or 5 times the width of the lines ; 

 there is a very slight and gradual constriction, most apparent 

 near the outer lip, about the middle of the body, and in front of 

 this the shell is slightly tumid. Colour translucent white, with 

 vague trace of spiral bands. Mouth the full length of the shell ; 

 shaped like a racket, being oval in front, long and narrow above ; 

 it is small and rounded at the top, which just rises to the crown. 

 Whorls 4, of which only the small rounded tops are seen on the 

 crown, where they are slightly and radiatingly ridged, the last 

 envelopes all the others. Suture impressed and distinct. Oicter 

 lip rounded at the top, where it does not rise above the crown ; 

 it runs straight and parallel to the inner lip till below the middle, 

 where it bends outwards in exact symmetry with the correspond- 

 ing bend of the inner lip on the base, forming a very regular 

 oval curve in front ; the edge line is regularly curved, retreating 

 slightly behind and in front, and advancing in the middle where 

 the lip is contracted. Top flat, but slightly depressed, with a 

 small papillary apex in the middle, the outer edge is roundly 

 angulated. Inner Up straight down the body, concave on the 

 pillar, which has a very slight twist and a narrow patulous edge, 

 behind which is a scarely appreciable umbilical depression ; the 

 point of the pillar projects in front clear of the sweep of the 

 basal curve. L. 0'12. B. 0"06. B. of mouth at same place, 

 002. 



This species is very like Z7. truncatulus, Brug. ; but that has 

 much stronger longitudinals, no spirals, and its crown is oblique, 

 sloping down from left to right, on which side the top of the 

 mouth and outer lip rise in a rounded looj) very considerably 

 above the top of the body-whorl. 



13. Uteiculfs oetctus, n. sp. {opvKros, excavated.) 

 St. 344. Aijril 3, 1876. Lat. 7° 54' 20" S., long. 14° 28' 20" W. 

 Ascension Island. 420 fms. Hard ground. 



