CERITHIOPSIDES i'ROM THE NORTH ATLANTIC. 93 



whorls ; and these threads form a more prominent feature than 

 the longitudinal riblets ; their intersections are marked by 

 square flat-topped largish tubercles. The upper thread becomes 

 broader down the spire, and splits into two approximate tubercled 

 threads ; so that on the last whorl there are three rows of 

 tubercles. The lowest thread has a strong furrow below it 

 within the contraction of the base; below this furrow is a 

 large tubercled thread (which does not appear in the figure) 

 occupying nearly the entire base ; crowded in on the foot of 

 the pillar is a small thread, darker than the rest. The twisted 

 pillar is very short and stumpy (very much more so than the 

 figure represents), and the canal lies quite in behind it. The 

 whole shell is of a rich glossy dark-chestnut colour. The suture 

 is deeper and less broad than in the figure. 



Hah. The Mediterranean. One rubbed specimen was found 

 by Mr. Clark at Exmouth : it had probably been imported. 



I owe a sight of the Mediterranean specimen of this species to 

 the kindness of the Marquis of Monterosato, to whose promised 

 monograph I must refer for a figure of this form. The figure in 

 the ' British Mollusca ' leaves very much to be desired ; it wants 

 the apex, it presents a quite fictitious mouth and pillar, and fails 

 to catch the general sculpture and the ornamentation of the base. 



(8) C. DiADEMA, Wats. (See Monterosato, Jo urn, de Conch. 

 1874, p. 273, No. 167.) 



Has a long, narrow, cylindrical, barely conical apex of four 

 whorls, of which the tip is blunt, rounded, and finely spiralled ; 

 and is followed by three feebly convex whorls parted by a very 

 slightly impressed suture : these whorls are on the upper part 

 very finely scored with longitudinal riblets, and near the bottom 

 are keeled by a sharp angularly projecting spiral thread. 

 On the base of the shell there are two circumbasal spiral 

 threads, the outer of which lies close to the lowest of the 

 lateral spirals, and is feebly tubercled ; the inner spiral is rather 

 prominent, lies well within the base, and is separated from the 

 outer by a broadish but rather shallow furrow ; within it lies 

 the flat, barely depressed centre of the base encircling the pillar. 



Hah. Madeira, to 50 fathoms (Watson); Palermo, Sicily, 

 54 fathoms (Monterosato). The ' Porcupine ' got it in 1870 

 at Benzert Eoad in 40 to 65 fathoms; at Easel Amoush, 45 

 fathoms ; and on the Adventure Bank in 92 fathoms, Medi- 

 terranean. 



