The Invertebrate Fauna of the Uitcnhacje Scries. 177 



which may possibly belong to this species, though it possesses certain 

 distinguishing characters which are noted below. 



Remarks. Sharpe's figured type, in the collection of the Geological 

 Society of London, is an unsatisfactorily preserved immature speci- 

 men with the shell partially removed. The smallest example sent 

 to me from South Africa measures 6'5 mm. in length, and is con- 

 siderably larger than the figured type, but a careful comparison 

 convinces me that these and the larger shells, one of which attains 

 a length of 19 mm., represent the same form. All the specimens 

 submitted to me have their whorls covered throughout with the 

 delicate spiral striae, and it was probably the imperfect preservation 

 of his material which led Sharpe to believe that these markings are 

 confined to the lower part. Eelatively to the size of the whorls, the 

 spiral ornamentation is strongest in youthful and early adult stages, 

 weakest in the last whorl. A single specimen collected by Mr. 

 Eogers (95h) differs from the majority of the individuals examined 

 by its taller spire, narrower spiral angle and less inflated body- 

 whorl : the degree of overlap in the whorls is also rather less, 

 and the body-whorl occupies less of the total height of the shell 

 (see plate viii., fig. 17). This may possibly represent a distinct 

 species, but it bears so close a general resemblance to A. atJierstoni 

 that it is difficult to arrive at a decision on this point, especially as 

 some variation is observable in the other individuals. 



The examination of well-preserved adult specimens shows that 

 this species possesses a mouth of oval form, rounded below, with 

 sharp outer lip and a columella quite devoid of folds. It therefore 

 falls within d'Orbigny's genus Actaonina as restricted by Meek, :;: 

 under which name it was correctly quoted by Messrs. Rogers and 

 Schwarz in their report on the survey of 1900. 



There is some resemblance between Actceonina atherstoni and the 

 Belgian shells ascribed by Briart and Cornet t to the Blackdown 

 species named Phasianella striata by J. de C. Sowerby, and 

 described under d'Orbigny's name Phasianella soiverbyi.\ This 

 has a shorter spire than the African form, but to judge from the 

 figures given by the Belgian authors, the slender outline of the shell 

 and the shape of the mouth are very similar, although the two forms 

 are perhaps not even generically identical, and the striae are coarser 

 in the Belgian shell. In another Blackdown species, described by 

 Sowerby under the name Phasianella formosa,^ the shape of the 



* Meek (1), p. 91. f Briart and Cornet (1), p. 35, pi. iii., figs. 20, 21. 



t d'Orbigny (4), vol. ii., p. 152. 



J. de C. Sowerby (2), p. 343, pi. xviii., fig. 14. 



