THE 
MONTHLY MICROSCOPICAL JOURNAL. 
APRIL 1, 1877. 
1.—Additional Note on the Identity of Navicula crassinervis, 
Frustulia Saxonica, and N. rhomboides. 
By Rev. W. H. Dauuinearr, V.P.R.M.S. 
(Read before the Royau Microscopican Society, March 7, 1877.) 
PuaTE CLXXVI. 
Ir would have been a matter of much interest to me to have been 
present at the discussion which followed upon the reading of my 
paper upon the above subject in December last. I might have 
been able to afford or to evoke explanation that would have served 
to further elucidate the subject. 
it The only report of the discussion I have access to is that given 
in the January number of the ‘M. M. J.,’ which doubtless is sub- 
stantially correct. In the interests of science, and with a simple 
desire to elicit truth, | may be permitted the privilege of this note 
upon some of the statements it contains. 
And first, of course my paper did not aim at proving, or, on 
my own authority, even asserting, the ¢dentity of the diatoms in 
question. I simply accepted this on the authority of Professor 
H. L. Smith and Mr. Kitton, which to myself was, and still is, per- 
fectly competent. But accepting the identity of these forms thus 
established, I sought to augment its value by a fact—in itself of 
some optical interest—that all these forms were in ultimate struc- 
ture precisely alike; so that, using the lowest power that would 
reveal the beaded arrangement on the surface of the smallest forms, 
we could, by using successively larger forms, with the same power, 
see precisely the same arrangement with increasing clearness and 
ease. 
DESCRIPTION OF PLATE CLXXVI. 
Fic. 1, A, B, C, D.—Four forms of NV. rhomboides in a gathering from “ Cherry- 
field,” showing modifications of outline, with the existence of the links uniting the 
two extremes (A and D). @ in A shows that the striation was that belonging to 
N. rhomboides. 
Fic. 2.Similar examples from specimens taken in the living state at Llyn- 
cum-Bychan. — ‘ ; 
Fic. 3.—Similar evidences of change of form in the smaller frustules known 
as IV. crassinervis. en 
Fic. 4.—Different modifications occurring in the apexes A, B, C, of the mid- 
ribs of these diatoms. 
VOL. XVII. O 
