Notes on Raputia aromatica. 97 



On account of its resemblance to two well-known genera, 

 namely, Trochus and Rotella, to neither of which can it, with 

 propriety, be referred, I have thought it necessary to give it 

 a generic appellation ; and for this purpose, I have chosen 

 Trochiscus, (from Tpo^o-yioe, Rotula). I would have used the 

 word Rotula, but that it is preoccupied, or a corruption of it, 

 for one of the most nearly cognate genera, {Rotella). 



^m^ 10 



Trochiscus Norrisii, Sowerby. 



TROCHISCUS. 



Char. Gen. Testa suborbicularis, depressiuscula, crassa, umbilicata, in- 

 tus margaritacea, spira brevi, conica, obtusa ; apertura subtrigonali, posti- 

 ce subacuminata, angiitis rotundatis ; labio columellari incrassato, antice 

 obsolete unituberculato ; umbilico majusculo, profundo. 



I have designated this very curious and rare shell, by the 

 specific name of Trochiscus Norrisii, in honour of the gentle- 

 man to whose liberality I am indebted for the opportunity of 

 describing it. 



In its general form it approaches very nearly to Rotella, 

 but differs from that genus in having a rather large and deep 

 open umbilicus. The shell is nearly smooth ; its lines of 

 growth are, however, distinct, but not prominent. Its outer 

 coat is of a chesnut brown colour, but the inside is of a bril- 

 liant pearly lustre. The border of the outer lip is nearly black, 

 that of the inner lip is green, and the inside of the umbilicus 

 is nearly colourless. Width 1.7, axis, 1.3 inches. 



Art. XI. Notes on Raputia aromatica. By Mr. Thomas 

 Hancock, M.B.S. 



The natural affinities of Raputia are extremely equivocal, 

 and have puzzled the brains of more botanists than one. Sir 

 J. E. Smith considered the plant as strictly allied to Euphor- 

 bia, whilst Decandolle insisted on its relationship to the Si- 

 marubem. Jussieu, however, placed it in the second tribe, 



