W. S. Sudleston— Gaderopoda of the Portland HocIiS. 395 



separated by a well-marked suture (Fig. 7c), and ornamented with 

 curved scaly marks, which are strongest on the flat posterior area 

 of the body- whorl. The nucleus is represented by a little knob in 

 the centre. The body-whorl is large, and its flanks are rather 

 strongly marked by lines of growth in connexion with the scaly 

 marks on the flat posterior area. The aperture is long, and the 

 outer lip nearly straight for two-thirds of its length, when it curves 

 round with an oval sweep anteriorly. The columella is much 

 excavated antei'iorly, but there is no distinct plication on the inner 

 lip, and the traces of an umbilicus are very faint. Shell thin. 



Belaiions and Distribution. — In form and general character this 

 fine species approaches Tornatina Bayani, Lor., from the Lower 

 Portlandian of Terlincthun (Boulonnais), but that species is only 

 6 "5 mm. in length, and is much longer in proportion to its width 

 than the Chilmark shell, which may be regarded as intermediate 

 between the above and such a form as Actceonina ventricosa, D'Orb., 

 quoted from the Upper Portlandian of Boulogne. It may be worth 

 mentioning that Tornatina Bayani occurs in the Pteroceras schichten 

 (Middle Kimmeridge) of Hanover, where it attains a length of 7 mm. 



Actceonina signitm (De Loriol would probably regard it as Torna- 

 tina^ is moderately plentiful in the highest portion of the C?/re?ia-beds 

 of the Vale of Wardour, towards the junction with the Chalky series 

 (No. 2), It has not yet been noted out of the Yale of Wardour. 



There is at least one other well-marked species, which is most 

 probably an Actceonina, from the same beds, and I have a large 

 specimen of an Acto^,onina in flint, which was most probably derived 

 from the Chalky series (No. 2). We may therefore regard this 

 group of the Actasons as being tolerably well represented in the 

 Portlandian of the Vale of Wardour. 



EXPLANATION OF PLATE XL 

 G. 1. Furpiiroidea Portlandica, Hudleston. la. Front view, lb. back view 

 of shell, nat. size. Portland Limestone, Ashendon, Bucks. 



2. Pseuclonielania ? percincta, Hudleston. 2a. Front view, lb. back view of 

 shell, nat. size. Cyrena-beds, Alford Quarry, near Tisbury. 



3. Ghemnitzia teres, Hudleston. 3a. front, 36. back view, nat. size. 

 Cyrena-beds, Chilraark Quarry. 



4. Natica incisa, Blake (1880). 4a. front, 45. back view, nat. size. Cyrena- 

 beds, Alford Quarry, near Tisbury. 



5. Neritoma sinuosa, Sowerby (1818). 5a. front, bb. back view, nat. size. 

 Cyrena-beds, Vale of "Wardour. 



6. Fseudomelmiia rugosa, Hudleston. 6a. front, %b. back view, nat. size. 

 " Creamy Limestones," near Aylesbury, Bucks. 



7. Actmonina signwn, Hudleston. 7a. fi'ont, "ib. back, 7c. apical view, nat. 

 size. Cyrena-beds, Chilmark Quarry. 



8. Natica elegans, Sowerby (1835). 8a. front, 85. back, nat. size. 

 " Creamy Limestones," Bucks. 



9. iVenVa ^ra^iswr.sa, Von Seebach (1864). Dorsal view, nat. size. Cyrena- 

 beds, Vale of Wardour. 



10. Chemnitzia naticoides, Hudleston. 10a. front, 105. back view. Cyrena- 

 beds, Chilmark Quarry. 



11. Chemnitzia decussatn, Hudleston. 11a. front, 115. back view. lie. 

 umbilical view, nat. size. Cyrena-beds, Chilmark Quarry. 



12a. and 5. Chemnitzia sp. ? Cyrena beds. Vale of Wardoiu-. 



