REPORT ON THE GASTEROPODA. 547 



11. Bittium gemmatum, Watson (PI. XXXIX. fig. 2). 



Cerithium {Bittium) gemmatum, Watson, Prelim. Report, pt. 5, Joum. Linn. Soc. Lond., vol. xv. 



p. 113, sp. 14. (Not Cerithium gemmatum, Hinds, "Sulphur" 



Exped., p. 47, pi. xi. figs. 5, G.) 

 Cerithium Watsoni, 1 Gwyn Jeffreys, "Lightning " and " Porcupine " MolL, Proc. Zool. Soc. Lond., 1884, 

 p. 56, sp. 8, pi. vi. fig. 6. 



Station II. January 13, 1873. Lat. 38° 10' N., long. 9° 14' W. Setubal. 470 

 fathoms. Green mud. 



Habitat. — Off the Southern Spanish coast at various of the " Porcupine " Stations, in 

 from 27 to 994 fathoms (Jeffr.) 



Shell. — High, conical, not narrow for the genus, blunt, with straight outlines, distinct 

 suture, rounded base, tubercled, thin, translucent white. Sculpture: Longitudinals — the 

 whorls are crossed by oblique, curved, and tubercled ribs, of which there are on the last 

 whorl 17, on the preceding 14, and they diminish rapidly in number. They are quite 

 obsolete near the mouth, and die out on the base ; they are parted by open longitudinal 

 furrows fully wider than themselves. The furrows and ribs run down the spire from whorl 

 to whorl without a twist, but with a strong sinistral obliquity. There are a very great 

 many fine irregular and unequal lines of growth. Spirals — each whorl is carinated by 

 two strongish rounded spiral threads, which rise into largish tubercles on the longitudinal 

 ribs ; the upper is rather the stronger and more prominent ; near the mouth they both 

 become feebler : the tubercles on the upper thread are smaller, while on the lower they 

 disappear. These spirals are parted by a flat shallow furrow about twice as wide as 

 themselves. Below the under spiral the whorls contract into the suture, above which is a 

 very narrow flat thread, which on the base forms the strongish marginal border. Above 

 the upper spiral the whorls also contract, and immediately below the suture there is a very 

 small and feebly tubercled spiral. On the base, within the marginal thread, is another. 

 The centre of the base is plain and a little impressed ; here there are two fine threads, 

 while a third, very minute, twists round the pillar itself. The whole surface is fretted 

 with minute microscopic spiral scratches. Colour translucent white. Spire is high, and 

 has straight outlines. Apex, which is blunt and perfectly rounded and glossy, has two 

 whorls. Wliorls 12 in all, of regular increase, convex, being constricted above and below. 

 Suture linear, but well marked. Mouth oval, scarcely pointed above, and with an open 

 shallow canal in front, resembling that in Bittium reticulatum. Outer lip very thin, 

 very slightly ascending where it joins the body, forming an equable, nearly semicircular 

 curve to the edge of the canal. Pillar very short and little projecting, with a distinct 

 twist ; at the point small, rounded, and narrow-edged. Inner lip forming a continuous 

 curve across the body and up the pillar ; on the body it is a thin glaze, but its edge on the 

 1 This change is unnecessary, as Hind's species is not a Bittium. 



