270 MR. E. A. SMITH ON THE [Ap""' 1' 



Operculum calcarium, ex anfraclihus duobus constitum, infenie 



leeve, incrementi liiieis striatum, extus porcis spiralibus scjiteiiis 



valde incequalibus, sulcis interjicientibun profundis, instruclum, 



(Plate XXI. fig. 14 a.) 



In sttjle of coloration this species resennbles N. tceniata, the 



well-known species from the Indian Ocean and the Philippines. It 



is, liowever, of a slightly different form, and the colour, both 



externally and within the aperture, is dissimilar. The two forms are 



at once distinguishable by the opercula. 



The operculum of N. taninta (Plate XXI. fig. 1.5) is externally 

 grooved and ridged, like that of N. turtoni, but the ridges are more 

 numerous and more equal in size. The figures on Plate XXI. show 

 at a glance the difference. The operculum of N. tceniata has not 

 previously been described. The specimen figured was collected at 

 Aden by the Rev. A. W. Baynham, who, in 1 885, presented to the 

 British Museum a very interesting series of shells from that locality. 



Natica dillwynii, Payraudeau. 



Hab. Mediterranean in many places ; Mauritius {Ilobillard) ; 

 South Pacific Islands {B. B. Woodward). 



After carefully comparing Maltese specimens of this species with 

 exanij)les of the West-Indian A', proxima of C. B. Adams, I am 

 quite convinced that they all belong to one and the same species. 

 Philippi (see Kiister's Conch .-Cab. Monog. Natica, p. 123) holds 

 them distinct, observing that N. proxima is more ovate in form, and 

 that the umbilical ridge is much thicker and situated below the 

 middle of the umbilicus. In answer to this, I would observe that 

 these differences do not exist in specimens in the Cumingian Collec- 

 tion, sent by C. B. Adams himself. None of the St. Helena 

 sj)ecimens are full-sized, but several are very brightly coloured. 



In the British Museum is a single specimen sent direct from the 

 Mauritius by M. Bobillard, which is absolutely identical with West- 

 Indian examples with which I have compared it, and specimens from 

 the South-Pacific Islands shown to me by Mr. Woodward seem to 

 belong undoubtedly to this species. 



Natica sanct^-helen^. (Plate XXI. fig. 16.) 



Testa parva, mnbilicata, globularis, nitida, albida, zona interiupla 

 rufo-fusca infra suturam cincta, lineis pallidioribus, ziczac- 

 formibus, prope umbilicum saturatioribus, zonum indistinctam 

 formantibus, ornata ; anfiactus 5, rapide accrescentes ; spira 

 jmrva, parmn prominens ; umbilicvs parvus, callo columellari 

 albido semiobiectiis ; apertvra semicircularis. 

 Alt. 9 millim., diam. max. 9. 



This species probably attains a larger size than the above dimen- 

 sions indicate. It resembles N. alderi of Forbes iu form, excepting 

 that the tip of the spire is scarcely so pointed, but the style of 

 markings may be sufficiently different to distinguish it. Besides the 

 rich brown, more or less interrujjted zone beneath the suture, and 

 the less distinct one around the umbilicus, the angles of the zigzag 



