348 MARSHALL: ADDITIONS TO “ BRITISH CONCHOLOGY.” 
rarely it is suborbicular. Some of the young approximate 
to Montacuta dawsont outwardly, and may easily be mis- 
taken for that species. The largest come from Jersey and 
Guernsey ; a valve from the latter island is a line in length, 
by a line and a half in width. 
Jeffreys’ figure is fairly good, but it should show a slight 
angularity at the posterior or smaller end, as in Sowerby’s ; 
and it is not concentrically striated as his section shows, 
but has irregular lines of growth, as shown in Sowerby’s 
figure. The latter, however, has the beaks too sharp and 
prominent. 
Scintilla eddystonia Marsh.—(J. of Mal, vol. 4, no. 2, pp. 
35-36, fig. 1). Eddystone, Land’s End, and Guernsey. 
Mr. Chaster, in a note to the above journal for Dec., 
1895, endeavours to show that this is the young of Dzp/o- 
donta rotundata; but he is very inaccurate. In the first 
place, he writes of a Scacchia eddystonia, though I have 
never described any .Scacchia; what I did describe was 
Scintilla eddystonia, and when he says this is “at once seen 
not. to be a Scacchia at all,” I quite agree with him. 
Secondly, he says my shell ‘closely resembles in shape 
Scacchia elliptica,” which it certainly does not. Next, he 
assumes my description of the dentition to be ‘ incorrect,” 
and states that the “two cardinal teeth are a single car- 
dinal,” and the ‘‘lateral tooth is another cardinal,” not- 
withstanding which infallible statement the cardinals and 
laterals I stated are there. Fourthly, as to Jeffreys’ figure 
of Diodonta baricet (Diplodonta jay.) being “not very 
good,” it could not be better; it corresponds exactly with 
Barlee’s specimens, with Sowerby’s figure, and with the 
umbonal area of adult-Diplodonta, but not with Sczztella 
eddystonia, the differences in which would strike the most 
superficial observer. 
It is a necessary qualification in criticising a writer for 
the censor to be himself correct, and though it is quite 
J.C., viii., Jan., 1897. 
