322 COOKE: ON THE GENUS PURPURA. 



of particular genera has at present fallen in my way. I venture 

 therefore to offer the following notes on the genus Purpura 

 proper, in the hope that the example may be followed by other 

 students better qualified than myself to pronounce on other 

 genera. 



Vol. II. p. 1 60. — P. persica L. '■ P. inerjna Reeve does 

 not differ.' 



This is a serious error. Tryon has been misled by the 

 somewhat patulous mouth and the dashes of white on the body 

 whorl o{ inenna, which, in a figure, suggest a momentary rem- 

 iniscence of persica. He cannot have seen shells named from 

 the type, which is as different as possible from persica in sculp- 

 ture (particularly of the spire) and coloration. The outer lip 

 of persica is invariably deeply stained inside with chestnut, 

 while the whorls are ringed with narrow bands in which white 

 and chocolate succeed one another with great regularity. 

 Neither of these characteristics are present in inerma, which 

 has also a much higher spire. I regard the species {inetwa, by 

 the way, is a strange mistake for i/ierinis, i.e. ' destitute of 

 tubercles ') as a non-tuberculated variety oi P. biserialis Blainv., 

 which is the West Coast American form of haemastoma L. The 

 locality, unknown to Reeve, is probably Ecuador. A tablet in 

 the British Museum gives Bay of Panama (Cuming), where I 

 can vouch for its not occurring. D'Orbigny's collection in the 

 same museum contains specimens (labelled P. haeinastoina) 

 said to be from Brazil, but it is very doubtful whether this form 

 of haemastoma occurs on the Western shores of the Atlantic. 



I do not advance this view of the true position of inerma 

 without having examined hundreds of specimens of P. biserialis, 

 and it must be recollected that the Purpura group is peculiarly 

 liable to variation in the tubercles with which so many of the 

 species are decorated. 



Page 161. — P. coliunellaris Lam. ^ P. leucostoma 'Desh. 

 does not present any well-marked distinctive characters.' 



J.C, v., July, 1888. 



