370 MARSHALL: ADDITIONS TO “ BRITISH CONCHOLOGY.” 
Var. distorta Jeff. (zon Poli).—‘‘1 still believe this to be a 
variety of 7. donacina, but in deference to other concholo- 
gists I will retain it as a provisional species. The difference 
seems to consist in the smaller size and greater angularity 
of the posterior side. It may be as distinct as 7. 
pusilla.” —(Jeffreys*). 
Judging from the few specimens I have seen of this 
variety, I do not consider the British form to be identical 
with the Mediterranean one, though it leads up to it. 
The fact is, that while some specimens of TZ. distorta 
are deeper from the beaks to the lower margin, other 
specimens of 2: donacina are narrower than the type 
form, and the differences between these two species being 
founded mostly on their relative proportions, this brings 
the two so close together that at first sight the extreme 
forms may easily be taken for one species. But I feel sure 
that Z. distorta is not a British shell—what Jeffreys has 
taken for such being a narrow form of Z. donacina. I am 
confirmed in this opinion by finding that the latter has its 
analogue in Z: pusilla. 
T. pusilla Phil.—Herm Island, low water ; off Scarborough, 
30 f.; the Minch off Barra, 30—50 f. The latter are very 
large— 44 lines by 3. 
Admiral Bedford informed me that he once picked up 
forty dozen on the beach in Sinclair Bay, Scotland. 
A perfect specimen and two valves of Z. calaria 
Chem. are in the MacAndrew Collection from Loch Fyne; 
Doggerbank, an imperfect valve (Jeffreys); Sutherland- 
shire, from fish stomachs (Baillie)! Aberdeenshire and 
Sutherlandshire, valves adherent to star-fish. None of the 
above can be pronounced recent. 
Psammobia tellinella var. gracilis Jeff.—Smaller, shorter, 
and not so angular. It has a slight gape at each end, but 
* Moll. ‘ Lightning’ and ‘ Porcupine,’ Proc. Zool. Soc., 1881, p. 721. 
J.C., viii., Apr. 1897. 
