ol 
Dr. John Bigsby, in his “ List of Organic Re- 
mains, occurring in the Canadas,” states that the 
A. caudatus is frequently met with, thrown up by the 
water on the north shore of Lake Superior—on the 
bank of Rainy river—at the Lake of the Woods, and 
at several other places. In some localities they are 
astonishingly numerous, and so small as to be almost 
microscopic. They occupy indiscriminately lime- 
stone of every colour, but are most numerous in that 
which is brown or crystallized. They are composed 
of the kind of limestone in which they ee to be 
embedded. 
We have seen a number of specimens of this species 
in the Albany Institute, in Mr. Wetherill’s cabinet, 
and in the Baltimore Athenzum; but in all of them, 
the abdomen and caudal extremity only remain fer- 
fect: from their exact resemblance, however, to the 
same parts of the A. caudatus, figured by Broneniart, 
(plate 2, fig. 4,.D.) we have no hesitation with regard , 
to their identity. The description which we have 
given of the buckler, supposed to belong to our Asaph, 
is therefore taken from Brongniart, whose specimens 
were found at Dudley, the celebrated locality of the 
C.Blumenbachii.* The coriaceous membrane, which | 
extends beyond the lateral lobes and ohske the caudal 
* In the first volume, 2d series, of the Transactions of the 
Geological Society of London, Mr. Weaver has published some 
highly interesting observations on the fossils found in Glouces- 
tershire, England. The A. caudatus, he states, is there found 
in the transition limestone, though very much mutilated. (Vide 
p. 326.) 
