TURRILITES. 05 



to form a mouth like an adult, with the ribs becoming flexuous. A still younger shell, 

 with the produced mouth completed, is shown in fig. 3 ; but as this specimen has the 

 lower side of the whorl strongly ribbed, it may be doubted whether it belongs to the 

 same species. 



5. Turrilites Morrisii, Sharpe. Plate XXVI, figs. 4 — 8. 



T. testa turritd, sinistrorsd : anfractibus numerosis, extra planiusculis tuber culatis : 

 tuberculis 3 vel 4 serialibus; serie superiori, in medio anfractuum, tuberculis 8 — 12 

 majoribus, distantibus ; seriebus inferioribus prope suturam, tuberculis minoribus, numerosis: 

 angulo spirali 1 5°. 



Shell turreted, with a spiral angle of about 15°, sinistral: whorls numerous, nearly flat 

 externally, with one row of 8 to 12 large tubercles near their middle, and two or three 

 rows of above 20 smaller tubercles near the suture, all of them with a round base : upper 

 and lower sides of the whorls ornamented with faint, radiating ribs, corresponding to the 

 tubercles of the lowest row : umbilicus very narrow : section of the whorls rhomboidal : 

 septa with the superior lateral lobe bifid, with four branches on each side, and the dorsal 

 saddle divided into two very unequal parts : the perfect mouth has not been seen. 



In the young shell the three lower rows of tubercles are usually distinct; in older shells 

 the tubercles of the two lower rows gradually coalesce, and at last hardly more than one 

 row can be distinguished, close to the suture. 



Largest diameter, 1^ inch; probable length, 6 inches. 



Common in the Chloritic Marl of the Isle of Wight, and in the Chalk with siliceous 

 grains, Chardstock, Somersetshire. 



6. Turrilites Bergeri, Brongniart. Plate XXVI, figs. 9 — 11. 



Turrilites Bergeri, Brong. Env. de Paris, t. 7, fig. 3. 



IX Orb. Pal. Fran?. Terr. Cret., t. 143, figs. 3—6. 



T. testa turritd, sinistrorsd {vel dextrorsd ?) .- anfractibus paucioribus, rotundatis, tuber- 

 culatis : tuberculis 4 serialibus, aquidistantibus, aqualibus : aperturdrotundato-rhomboided. 



Shell turreted, turned to the left : whorls not very numerous, increasing rapidly in 

 size, rounded, and ornamented with four equidistant rows of numerous, rounded tubercles, 

 which are of the same number, and nearly the same size in each row ; only three rows are 



