Greville^ on New Diatoms. 
21 
especially when taken in connection with the constriction, 
which may be recognised throughout all the variations of 
each species. This, however, is only an impression produced 
on my own mind after, it must be confessed, a too limited 
suite of observations. I find that Dr. Wallich obtained an 
Amphiprora at St. Helena, which he also compared with 
A, maxima ; but he remarks in his notes, written at the 
time (accompanied by a very careful sketch), that the curve 
of the lobes is different. They appear, indeed, to differ 
both from those of A. maxima and the subject of the present 
notice. 
