68 FOSSIL MOLLUSCA OF THE CHALK. 



another, without ribs between them ; the tubercles of the two outer rows are smaller than 

 the others, and meet at the junction of the valves, forming a crenulated suture ; while the 

 tubercles of the two middle rows, which are nearly equal, are prominent on the side of the 

 whorls ; surface of the whorls between the the tubercles smooth ; aperture nearly square ; 

 umbilicus small. 



The largest specimen seen has a diameter of 1^ inch, which requires a length of 4 or 

 5 inches. 



As yet we have only seen it from the Chalk with green grains, where it is very 

 abundant. 



This elegant shell is at once distinguished from T. tuberculatus by having the same 

 number of tubercles in each row, in which it agrees with T. Bergeri. From this it differs 

 in the shape of the whorl, and the position of the lower row of tubercles, which is at the 

 suture instead of projecting at the side of the whorl : in consequence of this, it has only 

 two rows of tubercles visible instead of three on the side of the whorl. 



Found in the Grey Chalk, of Ventnor, Isle of Wight ; and also in the Chalk with green 

 grains, at Chardstock, Somersetshire; and at Chaldon and Man-of-War Cove, Dorsetshire. 



] 1 . Turrilites Puzosianus, D' Orb., var.? Plate XXVII, fig. 11. 



? Tukrilttks Puzosianus, D" Orbigny . Terr. Cret., pi. 143, figs. 1, 2. 



T. lestd turritd, sirnstrorsd ; anfractibus externi planiusculis, costulatis, tuberculatis ; 

 costis nu merosis, Jlexuosis, obliquis, sup erne interruptis tuber eulatisque ; tubercidis bi-seriali- 

 bus, seriis superioris biuis, inferior is longitudinaliter compressis ; aperturd ovali ; umbilico 

 parvo. 



Shell turreted ; spine turned to the left, with a spiral angle of about 15°; whorls 

 flattish, with the lower angle rounded oft', separated by a moderate suture, and ornamented 

 with numerous oblique, flexuous, slight ribs, interrupted near the top of the whorl by a 

 smooth spiral band, on each side of which the ribs rise into longitudinally flattened 

 tubercles ; the tubercles of the upper row bifid or double, and stand at the angle of the 

 whorl ; aperture somewhat oval ; umbilicus small. 



I have as yet only seen one fragment of this shell. It resembles T. Puzosianus, D'Orb., 

 in having ribs rising into tubercles on each side of a smooth band, which, running round 

 the upper part of the whorl, divides the ribs into two unequal parts. Our shell differs 

 from T. Puzosianus in the flexure of the ribs, and in the position of the upper row of 

 tubercles, which, in that species, is placed at the suture, and thus concealed by the next 

 whorl ; but in this one it is at the upper angle of the whorl, and always prominent. It 

 differs from T. coslahis in the flexure of the ribs and flatness of the whorls. 



Found in the Chloritic Marl, of Bonchurch, Isle of Wight. 



