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growth and development within of the future frustules, and ulti- 
mately to produce the “caps’’ seen in the other examples. In 
fact, the whole process seems to be quite like that described by 
Carter in Navicula serians (‘ Ann. and Mag. of Nat. Hist.,’ vol. 
xv, 3 ser., p. 161); probably, indeed, in general details all the 
navicular forms coincide. 
Mr. Archer drew attention to the incipient state of the conju- 
gation in a Pinnularia. Immersed in a common hyaline envelope, 
the conjugating frustules had commenced a mutual fusion of their 
contents extruded therefrom ; no further or more advanced stage 
had, he regretted to say, fallen under notice. 
Mr. Archer thought it might be worth while to draw attention 
to some examples of Olathrulina elegans (Cienk.), remarkable for 
their seemingly exceptionally large dimensions, being fully 45 
of an inch in diameter—more than twice, nearly three times, as 
great as any he had before noticed; the stipes appeared to be 
equivalently long and thick, but while the fenestrate “ skeleton ” 
was of a dark brown colour, the stipes were perfectly clear and 
colourless, and without any apparent structure, except that it 
appeared tubular. In some instances the fenestrate globes were 
closely filled with numerous encysted sarcode masses, not seem- 
ingly individually larger than the few or one only found in the 
similar condition of ordinary sized examples. 
