486 GASTROPODA. [Pectinibranchia . 



Subfam. 2. CLAVATCTLIN.E. 

 Operculum pyriform, with lateral internal nucleus. 



Genus 1. SURCULA, H. and A. Adams, 1853. 



Surcula, H. & A. Ad., Ad. G.R.M., i, 1853, 88. Type: Pleurotoma 

 javana, L. 



Animal with the eyes at the base of the tentacles. Formula of 

 teeth of radula 1+0+1 ; the teeth falciform. 



Shell elongated, fusiform or biconic ; spire turriculated ; proto- 

 conch smooth, conic, with a pointed nucleus ; whorls excavated 

 above, convex below, very often ribbed on the convex part and angular 

 or subcarinate below the shoulder ; suture margined by a smooth 

 cord ; aperture pyriform, with an inflected and anteriorly widened 

 canal, sometimes straight and narrow ; outer lip thin, smooth inside, 

 convex at the middle, with a deep sinus in the infrasutural depression 

 above the peripheral carina ; inner lip generally thin, narrow, ending 

 in a fine point below. 



Distribution. Warm eastern seas, chiefly the Indian Ocean. 



Fossil in the Tertiary. 



1. Surcula gypsata, Watson, 1881. Plate 21, fig. 13. 



Pleurotoma (Drillia) gypsata, Wats., J.L.S., xv, 1881, 413. Drillia gypsata, 

 Wats. : Hutton, P.L.S. N.S.W., x, 117. Pleurotoma (Surcula) gypsata, 

 Wats., Chall. Rep., xv, 297, pi. 25, f. 1. 



Shell strong, fusiform, biconical, scalar, shortly sharply and obliquely 

 ribbed, keeled, constricted at the suture, with a long and rather inflated 

 body-whorl and a longish canal. Sculpture : Longitudinals on each 

 whorl is a strongish angulation, forming a shoulder, crowned by a 

 series of narrow elongated tubercles or short ribs ; this coronated 

 keel lies on the earlier whorls below, but on the later above the middle ; 

 the ribs do not reach the lower suture ; they are irregular in shape, 

 swollen in the middle, the interstices nearly double their width ; on 

 the body-whorl they extend very little below the shoulder, and their 

 number is about 20, but on the spire- whorls only 15 ; the surface, is 

 covered with hair-like lines of growth. Spirals the whole surface 

 is covered with flatly rounded threads, roughened by the incremental 

 lines. Colour whitish under a yellowish epidermis, which is a rough 

 but thin and persistent membrane. Spire high, scalar, conical. Apex 

 eroded, but evidently small. Whorls about 10, of rather rapid increase, 

 high, angulated, with a long scarcely concave shoulder, slightly con- 

 tracted at the lower suture ; the last large in proportion. Suture 

 very slight. Aperture pale-buff-coloured within, long and narrow, 

 angulated above, with an elongated broad unequal-sided canal. 

 Outer Up slightly concave above, regularly curved from the keel to 

 the base. On leaving the body the line of the edge runs straight 

 forward for a short distance, and then curves round to the left, running 



