GREY CHALK MARL. 123 



Tab. xxiii. fig. 5, is the fragment of a very large hamite, nearly allied 

 to the preceding ; it was collected at Hamsey by Mrs. Mantell. 



Localities. Hamsey, Middlehara, Stoneham. 



42. Hamites baculoides, Tab. xxiii. figs. 6, 7. 



Cylindrical, elongated, marked with obscure, oblique, distant undula- 

 tions on the outer margin ; curvature ? septa distant. 



Fragments from one to six inches in length, and about 04 inch in 

 diameter, marked with obhque undulations, and occasionally exhibiting 

 foHaceous septa, are very abundant in every locality of the grey marl near 

 Lewes : those figured are the most perfect that have yet been discovered. 



This species may be easily recognized by its extraordinary length, by 

 the smoothness of its surface, and the great obliquity of the few undu- 

 lations with which it is ornamented. The form of the curvature is un- 

 known ; for although several hundred specimens have been examined, the 

 short fragment delineated in fig. 6, tab. xxiii. is the only known instance 

 of a deviation from a straight line. These remains are associated with 

 fragments of a large size, almost cylindrical, and perfectly smooth : are 

 these portions of the larger hmbs of the same species ? By an inadvertence, 

 the specimens are represented in the plate, with the largest extremity 

 downwards. 



Localities. In every marl-pit in the south-eastern part of Sussex. 



42. Turrilites* costatus. Tab. xxiii. fig. 15, Tab. xxiv. figs. 1, 4, 5. 



Volutions reversed, convex, ornamented with transverse ribs, beneath 

 which are two rows of tubercles. 



The upper half of each wreath is ornamented with about twenty 

 smooth, rounded costae, beneath which is a row of elliptical tubercles, and 

 a set of smaller ones on the inferior margin ; the latter are partly obscured 

 by the next whorl. In almost every example the costae, and tubercles, 

 pass into each other. 



The specimens that occur in Sussex, very rarely exceed three or four 

 volutions, and are always in some degree compressed ; they are from one 



* Turrilites. A spiral, turreted, multilocular univalve ; volutions contiguous and apparent ; 

 septa foliaceous, pierced near the upper margin by a siphunculus, aperture round; columella 

 smooth. 



R 2 



