On “ Navicula crassinervis,” &e. By W. H. Dallinger. 3 
onica,” was, what it had been by some competent judges affirmed 
to be, ‘a coarse form of Rhomboides.”’ Mr. Charles Stodder then 
adds a concise note,* giving reason and authority for believing that 
both N. crassinervis and F. Sawonica are but forms of N. rhomb- 
otdes; and Dr. H. L. Smith’s most valuable and conclusive letter 
follows ;¢ and in this it is shown that not only is there identity 
between the three diatoms in question, but that all important 
authorities, Rabenhorst excepted, are agreed in the admission of 
that identity. To this letter Mr. F. Kitton, who had been requested 
by Professor H. L. Smith to revise the proofs, takes the opportunity 
of stating that he fully agrees “that the genus Frustulia should 
be abolished ;” and he is also of opinion “that Navicula cras- 
sinervis 1s only a form of N. rhomboides.” He adds, “ I may 
also state that my friend Mr. Hickie is of the same opinion.” 
Clearly therefore Mr. Hickie’s conviction of the “very great dif- 
ference” existing between N. rhomboides (into which F. Saxonica 
had now been fused) had been overcome. The reasonings or facts 
which accomplished this in Mr. Hickie’s case are not given us; but 
his frankness and candour are sufficient evidence of the scientific 
spirit in which his inquiries were conducted. 
So far, it is clear, that these three diatoms are, on the best 
authority, accepted as mere conditions of the one form, N. rhomb- 
otdes. ‘The reasons for this decision have relation to morphology 
and development, quite as much as to the characteristics of the 
silicious skeleton with which the microscopist is more generally 
concerned. With the former of these reasons I may not concern 
myself, but receive them thankfully from competent authority. 
But with the latter facts I will venture briefly to deal. 
Nothing up to this time is finally before us, as to what kind of 
“resolution ” these various conditions of Rhomboides may be 
expected to yield, or what their real value, as tests, is. 
My first acquaintance with this diatom was made some eight or 
nine years since. It had lain in my cabinet for some years before 
this: but some exquisite specimens prepared and mounted by 
L. Hardman, Esq., were courteously given me by him, and I did 
my best at that time with them. They were what I presume have 
been called ‘‘ small Lhomboides” ; for the largest of them taxed the 
power I then possessed, to develop their transverse striz sharply 
and well, with a good English 1th, and the smaller of them were 
so fine, as to resist all the manipulative skill I then possessed with 
a ysth, and some of the minute ones, even with Powell and 
Lealand’s y';th (dry). 
Coming from so excellent an authority on diatoms as Mr. 
Hardman, I accepted these as normal specimens of the species ; 
and as my manipulative skill increased with practice, and my 
* “M.M. J? vol. xv. p. 265. + Ibid. p. 279. 
B 2 
