170 Annals of the South African Museum. 



ornamented by rounded, shallow spiral grooves, and blunt spiral 

 ridges having little prominence. These ornaments are so disposed 

 that above the peripheral area a weakly marked ridge forms the 

 outer limit of a narrow shoulder which is without spiral sculpture, 

 while on the lower part of the peripheral area is a spiral groove, 

 slightly broader than the three remaining grooves which lie below 

 it. The surface is crossed transversely by numerous and well- 

 marked ridges and furrows of growth, which are so regularly 

 developed as almost to appear to constitute part of the sculpture. 



Occurrence. This was found, in association with the three forms 

 previously described, in the cliff below the old school-house at 

 Dunbrodie, Sunday's Eiver (351). 



Remarks. This imperfectly preserved specimen is quite distinct 

 from the other forms assigned to the genus Turbo, described above, 

 but it will be well to await the collection of further material before 

 applying a specific name. It can hardly even be said that the generic 

 position is established beyond doubt. Although the rounded form 

 of the whorl and the impressed spiral grooves might suggest at first 

 sight that we are dealing with a fragment of an immature Neritopsis f 

 turbinata Sharpe,* a comparison with Sharpe's specimens shows 

 that this is not the case. The spiral ornaments lack the regularity, 

 and the grooves are broader, less sharply incised and less regularly 

 spaced than those of Sharpe's type. A complete comparison, it is 

 true, is difficult, since the examples of Neritopsis f turbinata pre- 

 served in the Geological Society's museum are all much larger than 

 the fragmentary specimen here described, and the involution of 

 Sharpe's shell is such that it is not possible to make satisfactory 

 comparison at the same stage of growth ; but the observable diffe- 

 rences in the ornamentation are in themselves sufficiently significant. 



Considerable resemblance is shown to a shell from the Neocomian 

 of German East Africa described by G. Muller as Delphinula afri- 

 cana t \ such similarity, in fact, as to suggest that we are dealing 

 with a closely allied form. The shape and proportions of the body- 

 whorl appear alike, and in each case there is the strong spiral groove 

 on the lower part of the peripheral area. In the figure of Delphinula 

 africana a spiral keel is seen, situated between this groove and the 

 keel which defines the shoulder above. In the Dunbrodie specimen, 

 which is of smaller dimensions than Miiller's type, the beginnings of 

 a similar keel, though weakly developed, are becoming apparent in 

 the most advanced portion of the whorl. As regards other charac- 



* Sharpe (1), p. 198, pi. xxiii., fig. 5. 

 t G. Muller (1), p. 557, Taf. xix., fig. 11. 



