TURRILITES. M 



T. testa elongato-turritd, sinistrorsd, costatd et tuberculatd ; anfractibus convexius cutis, 

 inferne costatis, superne bituberculatis ; costis tuberculisque numero aqualibus ; aperturd 

 ovali ; wnb'dico minimo. 



Shell turreted, turned to the left, with a spiral angle of about 25°; whorls slightly 

 convex, separated by a moderately impressed suture, and ornamented on their lower half 

 by numerous straight, elevated ribs, which rise at their upper ends into round tubercles, 

 and then terminate abruptly at a smooth spiral band, which encircles the shell ; above are 

 two rows of tubercles, the upper of which are smaller, and concealed by the next whorl ; 

 ribs and tubercles equal in number ; aperture oval, higher than broad ; umbilicus very small. 



[The complicated form of the septa in this species is represented in PI. XXVII, fig. 15. | 



In Dixon's ' Geology of Sussex,' a Turrilite is described under the name of T. tripli- 

 catus, J. Sow., which appears to be a variety of the above. [This specimen is figured in 

 PI. XXVII, fig. 15.] 



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

 grains, at Chardstock. 



9. Turrilites bifrons? V Orb. Plate XXVII , figs. 6, 7. 



[T. testa turritd, elongatd, sinistrorsd ; anfractibus convexiusculis, sulco tongitudinaliter 

 ornatis ; transversim costatis ; costis curvatis, interruptis, biseriatis, anterioribis ad 

 suturam divisis. 



The specimens figured differ from the ordinary examples of T. costatus in the flatten- 

 ing of the whorls, occasioned bv the shallow furrow which divides the curved transverse 

 ribs into a double series : the ribs are simple, rounded, and about as wide as the inter- 

 spaces ; the lower series of ribs is again divided by a furrow exactly at the suture, forming 

 a third set of little tubercles, only visible on the base of the shell when broken. 



Found in the Lower Chalk, of Ventnor, Isle of Wight.] 



10. Turrilites Wiestii, Sharps. Plate XXVII, fig. 8, 9 a, b, and fig. 17. 



T. testa turritd, sinistrorsd ; anfractibus externis rotundatis, tuber cutatis, intus lavibus ; 

 tuberculis conicis 4 serialibus, numero equalibus, superiore et inferiore minoribus, in sidurd 

 profunda crenulatd, coalescentibus, mediis binis majoribus prominentibus ; aperturd sub- 

 quadratd; tcmbilico parvo. 



Shell turreted, tuberculated ; spine turned to the left, with a spiral angle of about 22°; 

 whorls rounded, separated by a deep, crenulated suture, ornamented with four rows of 

 conical tubercles, which are of the same number in each row, and set obliquely under one 



