Mr. W. Clark on Assiminfa Grayana and Rissoa anatina. 115 



respecting the structure of the tcntacula and eyes, and its natural 

 position. The other, the Rissoa anatina, is a llissoidcan of the 

 group which is represented by R. ulva. Autliors have men- 

 tioned both these animals, and the Rev. M. J. Berkeley has pub- 

 lished a valuable memoir and figure of A. Grayana, in vol. v. 

 p. 429 of the ' Zoological Journal / but I have thought that the 

 addition of later notes on several unobserved points of this last 

 species, and in comparison with those of the genus Truncatella, 

 would be acceptable to some of your readers. 



In vol. xii. p. 4 of the 'Annals^ for July 1853, and in my 

 work above mentioned, pp. 380-6, I have expressed an opinion 

 that the genus Assiminia is superfluous, and that its only spe- 

 cies would be handed over to the genus Truncatella. I have 

 been so impressed with this view, that I invited malacologists 

 residing in the neighbourhood of Greenwich to send me live spe- 

 cimens of the A. Grayana; this request was inserted in the 

 'Annals,^ but the appeal remained unsuccessful until this date, 

 when I had the good fortune to obtain the long-sought-for desi- 

 deratum, with an unexpected addition of the Rissoa analiaa, 

 both in a living state, through the kindness of my friend John 

 Gwyn Jeffreys, Esq., of Swansea, who omits no opportunity nor 

 spares any personal exertion to add to his valuable contributions 

 to the molluscan branch of British natural history. 



Truncatella Grayana, nobis. 



Assiminia Grayana, auctorum ; Brit. Moll. vol. iii. p. 70. pi. 71. 

 figs. 3, 4 ; (animal) pi. H.H. f. 6. 



Shell, a short strong cone of 6^ tumid volutions, increas- 

 ing rapidly in bulk from the apex to the base, which are di- 

 stinctly but not deeply divided; each whorl is marked with a 

 somewhat irregular and confused rufous-brown and a yellow 

 spiral band, the former being the broadest, and situate at its 

 base ; the latter winds round the upper part, but in many ex- 

 amples the bands become so blended as to diffuse throughout 

 the entire area the mixed hues of the two fasciae. The trans- 

 verse strife of increment are well marked, and also obsolete 

 rather coarse spiral lines may be detected. Aperture suboval or 

 pear-shaped ; peristome disunited ; outer lip sharp ; no umbilical 

 fissure ; the apex is pointed. Axis y^^ths, diameter y o^h of an 

 inch. 



Animal. — The mantle at the aperture of the shell is simj)le. 

 The muzzle is very short and broad, flat, expanded, and curved 

 at the end on each side, forming minute auricles with a central 

 emargination or well-impressed sinuation, and furnished with 

 raised elastic annular lines that enable the animal to effect a 



8* 



