362 PLEUROTOMID.E. 



1. Defrancia teres"^_, Forbes. 



Pleuroto7na feres, Forbes in Ann. & Mag. IST. H. xiv. p. 412, pi. ii. f. 3. 

 Mangelia teres, F. L H. iii. p. 462, pi. cxiii. f. 1, 2, and (animal) 

 pi. RE. f. 3. 



Body white, minutely frosted : pallkd tube rather short : 

 head (or mentum) wedge-like, never protruded beyond the 

 foot : tentacles nearly cylindrical, of moderate length, widely 

 diverging, slightly scalloped at the edges ; tips blunt : eyes 

 small, on short stalks at the outer base of the tentacles: 

 foot deeply indented and angulated in front, with ear-shaped 

 and pointed corners which occasionally curl inwards and are 

 very flexible ; it is expanded at the sides, and tapers to a fine 

 point behind. 



Shell slender, rather thin, semitransparent, and somewhat 

 glossy : sculpture, numerous cord-like spiral ridges, which are 

 nearly always much broader than their insterstices ; from 20 

 to 25 of these ridges encircle the body- whorl, 8 to 10 the next 

 whorl, 6 or 7 the next, and others at the same rate of decrease 

 the remaining whorls ; many of those on the body-whorl 

 and all on the upper whorls are alternately large and small ; 

 the top whorls are minutely and closely reticulated by curved 

 cross striie in an exquisitely beautiful fashion ; the wide groove 

 immediately below the suture (which indicates the former 

 coui'se of the fissure characteristic of this genus) is marked 

 with close-set curved striae in the line of growth ; the rest of 

 the surface is thickly covered with oblique and microscopic lines 

 in the same direction: colour pale yellowish- white, prettily 

 but irregularly spotted with reddish-brown ; the spots appear 

 to be produced by interrupted longitudinal streaks; some 

 specimens are spotless ; apex yellowish-brown : sj)h'e elon- 

 gated and finely tapering: ivJiorls 10, convex and evenly 

 rounded ; the last occupies three -fifths of the shell viewed 

 mouth upwards, and about one-half of the shell in the contrary 

 position: suture very deep, formed by the fissural groove: 

 mouth pear-shaped; length a little more than two-fifths of 

 the shell : canal rather broad, a little inclining to the left, and 

 ending in a slight and obliquely curved notch : outer lip semi- 

 circular, furrowed within by the underside of the ridges ; edge 

 thin, scalloped or indented by the spiral sculpture : Jissure re- 

 markably distinct and broad, extending some way along the 

 suture ; its course can be traced throughout every part of the 



* ErOunded or well-turned. 



